Aripiprazole prodrug compositions

ABSTRACT

Described is a composition comprising (a) a population of particles of an aripiprazole prodrug having a volume based particle size (Dv50) of less than 1000 nm and (b) at least one surface stabilizer comprising an adsorbed component which is adsorbed on the surface of the aripiprazole prodrug particles and a free component available for solubilisation of the aripiprazole prodrug. The surface stabilizer to prodrug ratio provides the optimal quantity of free surface stabilizer for the purposes of producing a lead-in formulation. Also described are methods of treatment using the aforementioned composition.

This application claims priority from U.S. Provisional PatentApplication No. 62/038,665, filed Aug. 18, 2014. The contents of thisapplication is incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to compositions and methods of anaripiprazole prodrug. In particular, said compositions and methodscomprise an aripiprazole prodrug having a particle size of less thanabout 1000 nm and a surface stabilizer, wherein the surface stabilizerto prodrug drug ratio is between about 0.1:1 and about 40:1, mostpreferably about 17:1. The surface stabilizer to prodrug ratio providesthe optimal quantity of free surface stabilizer for the purpose ofproducing a lead in formulation.

BACKGROUND OF THE INVENTION

ABILIFY MAINTENA® (aripiprazole) extended-release injectable suspension,for intramuscular use, does not reach steady state plasma concentrationsin humans immediately upon its administration. Initiation therapy ofAbilify Maintena® requires 14 consecutive days of concurrent oralaripiprazole (10 mg to 20 mg) with the first depot dose to achievetherapeutic concentrations (Otsuka America Pharmaceutical, Inc.,“Abilify Maintena Product Insert, 2013”). Patient compliance during this14 day lead in period presents a challenge which the present inventionaddresses.

SUMMARY OF INVENTION

The present invention provides stabilized aripiprazole prodrugcompositions that can be tailored to have a desired initial in-vivorelease profile. In particular, the present invention providescompositions and methods that reduce the number of “lead in” days oforal aripiprazole required to achieve steady state plasmaconcentrations.

More specifically, the present invention provides a compositioncomprising: (a) a population of particles of an aripiprazole prodrughaving an volume based particle size (Dv50) of less than 1000 nm asdetermined by light scattering techniques, (b) at least one surfacestabilizer comprising an adsorbed component (i.e. quantity of surfacestabilizer) which is adsorbed on the surface of the aripiprazole prodrugparticles and a free component (i.e. second quantity of surfacestabilizer) available for solubilisation of the aripiprazole prodrug(i.e. the free stabilizer component is not adsorbed on the aripiprazoleprodrug particles). The ratio of aripiprazole prodrug to surfacestabilizer is between about 0.1:1 and about 40:1. The aripiprazoleprodrug has the formula:

where n is zero or an integer less than 20. In a preferred embodiment,the aripiprazole prodrug has the formula described above where n=4(aripiprazole cavoxil prodrug) or n=10 (aripiprazole lauroxil prodrug).In the above composition, the Dv90 of the composition may be less thanabout 1800 nm, preferably less than about 1500 nm and the Dv10 may beless than about 600 nm. Other exemplary particle sizes are describedherein. It is preferred that the composition is size stable.

The at least one surface stabilizer may be selected from the groupconsisting of a polyoxyethylene sorbitan fatty acid ester (e.g.polysorbate 80, polysorbate 40, polysorbate 20), low molecular weightpovidones, lecithin, d-alpha tocopheryl polyethylene glycol 1000succinate, dioctyl sodium sulfosuccinate, or docusate sodium), methyland propyl parabens, sorbitan monolaurate, carboxymethyl cellulose,hydroxypropylcellulose, sodium deoxycholate, akylsaccharides,difunctional block copolymers, d-alpha tocopheryl polyethylene glycol1000 succinate, gelatin, albumin, lysozyme, cyclodextrins an example ofwhich would be betahydroxcyclodextrin, and gel forming polymers. Theaforementioned are considered preferable from a safety standpoint.Preferably, the at least one surface stabilizer is selected from thegroup consisting of carboxymethyl cellulose and polyoxyethylene sorbitanfatty acid esters. The aforementioned surface stabilizers have beendemonstrated to be particularly effective in producing the stablecomposition of the present invention since the degree of particle sizegrowth in compositions including the above surface stabilizers was foundto be particularly low. More preferably, the surface stabilizer is apolyoxyethylene sorbitan fatty acid ester, for example polysorbate 20,since this is approved by the FDA for injectable use and was found to beparticularly effective in producing stable compositions.

The composition of the present invention may comprise only one surfacestabilizer, or may comprise a primary surface stabilizer and at leastone secondary surface stabilizer. The use of one or more additionalsurface stabilizers may improve the stability of the resultingcomposition and/or alter the in-vivo release of the aripiprazolepro-drug described herein.

A composition comprising more than one surface stabilizer may forexample comprise a primary surface stabilizer which is polysorbate 20and a secondary surface stabilizer which is pluronic F108 and/orcomponents thereof (the individual components being polyoxyethylene andpolyoxypropylene glycol). In such a composition, the aripiprazoleprodrug formula n is equal to 4 (i.e. aripiprazole cavoxil), and thevolume based particle distribution size (Dv50) of the aripiprazoleparticles is between 200 and 600 nm, preferably between 500 nm and 600nm. In such a composition the overall free component (made up from theprimary and secondary surface stabilizer) constitutes between 0.5% and10%, preferably 0.5% and 3% (w/w) of the composition.

The quantity of surface stabilizer to be added to the composition may beexpressed in terms of a ratio with respect to the quantity ofaripiprazole prodrug in the composition by calculating the percentage(w/w) (of the total composition weight including any excipients) of thearipiprazole prodrug and the total percentage (w/w) (of the totalcomposition weight including any excipients) of the surface stabilizer.If multiple surface stabilizers are present, the ratio takes intoaccount all of the surface stabilizers present in the composition. Theratio of aripiprazole prodrug to surface stabilizer is between about0.1:1 and about 40:1. The ratio of aripiprazole prodrug to surfacestabilizer present in the composition may more specifically be betweenabout 0.5:1 and about 38:1, about 1:1 and about 36:1, about 2:1 andabout 34:1, about 2:1 and about 25:1, about 2:1 and about 20:1, about4:1 and about 32:1, about 6:1 and about 30:1, about 8:1 and about 28:1,about 10:1 and about 26:1, about 10:1 and about 25:1, about 10:1 andabout 20:1, about 12:1 and about 24:1, about 13:1 and about 23:1, about14:1 and about 22:1, about 15:1 and about 21:1, about 16:1 and about20:1, or about 17:1 and about 19:1. In a preferred embodiment, the ratioof aripiprazole prodrug to surface stabilizer present in the compositionmay more specifically lie within the range from about 15:1 to about20:1. It has been found that this range provides the optimal quantity ofadsorbed and free component of surface stabilizer for the purposes ofproducing a lead-in formulation. Even more preferably the ratio ofaripiprazole prodrug to surface stabilizer present in the composition isabout 17:1.

In a composition having a volume based particle size (Dv50) of less thanabout 900 nm in size, the ratio of aripiprazole prodrug to surfacestabilizer present in the composition may be between about 0.5:1 andabout 38:1, about 1:1 and about 36:1, about 2:1 and about 34:1, about2:1 and about 25:1, about 2:1 and about 20:1, about 4:1 and about 32:1,about 6:1 and about 30:1, about 8:1 and about 28:1, about 10:1 and about26:1, about 10:1 and about 25:1, about 10:1 and about 20:1, about 12:1and about 24:1, about 13:1 and about 23:1, about 14:1 and about 22:1,about 15:1 and about 21:1, about 16:1 and about 20:1 or between about17:1 and about 19:1.

In a composition having a volume based particle size (Dv50) of less thanabout 800 nm in size, the ratio of aripiprazole prodrug to surfacestabilizer present in the composition may be between about 0.5:1 andabout 38:1, about 1:1 and about 36:1, about 2:1 and about 34:1, about2:1 and about 25:1, about 2:1 and about 20:1, about 4:1 and about 32:1,about 6:1 and about 30:1, about 8:1 and about 28:1, about 10:1 and about26:1, about 10:1 and about 25:1, about 10:1 and about 20:1, about 12:1and about 24:1, about 13:1 and about 23:1, about 14:1 and about 22:1,about 15:1 and about 21:1, about 16:1 and about 20:1, or between about17:1 and about 19:1.

In a composition having a volume based particle size (Dv50) of betweenabout 50 and about 700 nm in size, the ratio of aripiprazole prodrug tosurface stabilizer present in the composition may be between about 0.5:1and about 38:1, about 1:1 and about 36:1, about 2:1 and about 34:1,about 2:1 and about 25:1, about 2:1 and about 20:1, about 4:1 and about32:1, about 6:1 and about 30:1, about 8:1 and about 28:1, about 10:1 andabout 26:1, about 10:1 and about 25:1, about 10:1 and about 20:1, about12:1 and about 24:1, about 13:1 and about 23:1, about 14:1 and about22:1, about 15:1 and about 21:1, about 16:1 and about 20:1, or betweenabout 17:1 and about 19:1.

In a composition having a volume based particle size (Dv50) of less thanabout 700 nm in size, the ratio of aripiprazole prodrug to surfacestabilizer present in the composition may be between about 0.5:1 andabout 38:1, about 1:1 and about 36:1, about 2:1 and about 34:1, about2:1 and about 25:1, about 2:1 and about 20:1, about 4:1 and about 32:1,about 6:1 and about 30:1, about 8:1 and about 28:1, about 10:1 and about26:1, about 10:1 and about 25:1, about 10:1 and about 20:1, about 12:1and about 24:1, about 13:1 and about 23:1, about 14:1 and about 22:1,about 15:1 and about 21:1, about 16:1 and about 20:1, or between about17:1 and about 19:1.

In a composition having a volume based particle size (Dv50) of less thanabout 600 nm in size, the ratio of aripiprazole prodrug to surfacestabilizer present in the composition may be between about 0.5:1 andabout 38:1, about 1:1 and about 36:1, about 2:1 and about 34:1, about2:1 and about 25:1, about 2:1 and about 20:1, about 4:1 and about 32:1,about 6:1 and about 30:1, about 8:1 and about 28:1, about 10:1 and about26:1, about 10:1 and about 25:1, about 10:1 and about 20:1, about 12:1and about 24:1, about 13:1 and about 23:1, about 14:1 and about 22:1,about 15:1 and about 21:1, about 16:1 and about 20:1, or between about17:1 and about 19:1.

In a composition having a volume based particle size (Dv50) of less thanabout 500 nm in size, the ratio of aripiprazole prodrug to surfacestabilizer present in the composition may be between about 0.5:1 andabout 38:1, about 1:1 and about 36:1, about 2:1 and about 34:1, about2:1 and about 25:1, about 2:1 and about 20:1, about 4:1 and about 32:1,about 6:1 and about 30:1, about 8:1 and about 28:1, about 10:1 and about26:1, about 10:1 and about 25:1, about 10:1 and about 20:1, about 12:1and about 24:1, about 13:1 and about 23:1, about 14:1 and about 22:1,about 15:1 and about 21:1, about 16:1 and about 20:1, or between about17:1 and about 19:1.

In a composition having a volume based particle size (Dv50) of less thanabout 400 nm in size, the ratio of aripiprazole prodrug to surfacestabilizer present in the composition may be between about 0.5:1 andabout 38:1, about 1:1 and about 36:1, about 2:1 and about 34:1, about2:1 and about 25:1, about 2:1 and about 20:1, about 4:1 and about 32:1,about 6:1 and about 30:1, about 8:1 and about 28:1, about 10:1 and about26:1, about 10:1 and about 25:1, about 10:1 and about 20:1, about 12:1and about 24:1, about 13:1 and about 23:1, about 14:1 and about 22:1,about 15:1 and about 21:1, about 16:1 and about 20:1, or between about17:1 and about 19:1.

In a composition having a volume based particle size (Dv50) of between175 and 350 nm in size, the ratio of aripiprazole prodrug to surfacestabilizer present in the composition may be between about 0.5:1 andabout 38:1, about 1:1 and about 36:1, about 2:1 and about 34:1, about2:1 and about 25:1, about 2:1 and about 20:1, about 4:1 and about 32:1,about 6:1 and about 30:1, about 8:1 and about 28:1, about 10:1 and about26:1, about 10:1 and about 25:1, about 10:1 and about 20:1, about 12:1and about 24:1, about 13:1 and about 23:1, about 14:1 and about 22:1,about 15:1 and about 21:1, about 16:1 and about 20:1, or between about17:1 and about 19:1.

In a composition having a volume based particle size (Dv50) of less thanabout 300 nm in size, the ratio of aripiprazole prodrug to surfacestabilizer present in the composition may be between about 0.5:1 andabout 38:1, about 1:1 and about 36:1, about 2:1 and about 34:1, about2:1 and about 25:1, about 2:1 and about 20:1, about 4:1 and about 32:1,about 6:1 and about 30:1, about 8:1 and about 28:1, about 10:1 and about26:1, about 10:1 and about 25:1, about 10:1 and about 20:1, about 12:1and about 24:1, about 13:1 and about 23:1, about 14:1 and about 22:1,about 15:1 and about 21:1, about 16:1 and about 20:1, or between about17:1 and about 19:1.

In a composition having a volume based particle size (Dv50) of less thanabout 200 nm in size, the ratio of aripiprazole prodrug to surfacestabilizer present in the composition may be between about 0.5:1 andabout 38:1, about 1:1 and about 36:1, about 2:1 and about 34:1, about2:1 and about 25:1, about 2:1 and about 20:1, about 4:1 and about 32:1,about 6:1 and about 30:1, about 8:1 and about 28:1, about 10:1 and about26:1, about 10:1 and about 25:1, about 10:1 and about 20:1, about 12:1and about 24:1, about 13:1 and about 23:1, about 14:1 and about 22:1,about 15:1 and about 21:1, about 16:1 and about 20:1, or between about17:1 and about 19:1.

In a composition having a volume based particle size (Dv50) of less thanabout 100 nm in size, the ratio of aripiprazole prodrug to surfacestabilizer present in the composition may be between about 0.5:1 andabout 38:1, about 1:1 and about 36:1, about 2:1 and about 34:1, about2:1 and about 25:1, about 2:1 and about 20:1, about 4:1 and about 32:1,about 6:1 and about 30:1, about 8:1 and about 28:1, about 10:1 and about26:1, about 10:1 and about 25:1, about 10:1 and about 20:1, about 12:1and about 24:1, about 13:1 and about 23:1, about 14:1 and about 22:1,about 15:1 and about 21:1, about 16:1 and about 20:1, or between about17:1 and about 19:1.

The abovementioned ratio of active to surface stabilizer is selectedsuch that the appropriate level of free surface stabilizer is provided.The level of free surface stabilizer available should be sufficientlyhigh enough to achieve the desired modulation in pharmacokineticproperties, particularly onset time. However, the overall level ofsurface stabilizer in the composition is preferably low enough as toavoid toxicity problems or injection site reactions in patients. It ispreferred that the free component of the at least one surface stabilizerconstitutes greater than 0% (w/w) and no more than about 3% (w/w) of thecomposition (i.e. the overall weight of the composition including theactive, surface stabilizer and any other excipients added to thecomposition) as free surface stabilizer amounts in this range provideoptimal reduction in onset time whilst also being at a level which ispreferable from a toxicity perspective. The level of free surfacestabilizer may for example lie within the range of about 0.1 to about2.9%, about 0.1 to about 2.7%, about 0.1 to about 2.6%, about 0.1 toabout 2.4%, about 0.1 to about 2.2%, about 0.1 to about 2%, about 0.1 toabout 1.8%, about 0.1 to about 1.4%, about 0.1 to about 1.2%, about 0.1to about 1%, about 0.1 to about 0.8%, about 0.1 to about 0.6%, about 0.1to about 0.4%. More preferably, the quantity of free surface stabilizeris within the range about 0.1% to about 1.6%, as this particular rangehas been found to produce a significant reduction in the onset timewhilst at the same time ensuring that the level of surface stabilizerpresent is well within tolerable levels.

In a composition having a volume based particle size (Dv50) of less thanabout 900 nm in size, the level of free surface stabilizer may forexample lie within the range of about 0.1 to about 2.9%, about 0.1 toabout 2.7%, about 0.1 to about 2.6%, about 0.1 to about 2.4%, about 0.1to about 2.2%, about 0.1 to about 2%, about 0.1 to about 1.8%, about 0.1to about 1.4%, about 0.1 to about 1.2%, about 0.1 to about 1%, about 0.1to about 0.8%, about 0.1 to about 0.6%, and about 0.1 to about 0.4%(w/w) of the composition.

In a composition having a volume based particle size (Dv50) of less thanabout 800 nm in size, the level of free surface stabilizer may forexample lie within the range of about 0.1 to about 2.9%, about 0.1 toabout 2.7%, about 0.1 to about 2.6%, about 0.1 to about 2.4%, about 0.1to about 2.2%, about 0.1 to about 2%, about 0.1 to about 1.8%, about 0.1to about 1.4%, about 0.1 to about 1.2%, about 0.1 to about 1%, about 0.1to about 0.8%, about 0.1 to about 0.6%, and about 0.1 to about 0.4%(w/w) of the composition.

In a composition having a volume based particle size (Dv50) of between50 and 700 nm in size, the level of free surface stabilizer may forexample lie within the range of about 0.1 to about 2.9%, about 0.1 toabout 2.7%, about 0.1 to about 2.6%, about 0.1 to about 2.4%, about 0.1to about 2.2%, about 0.1 to about 2%, about 0.1 to about 1.8%, about 0.1to about 1.4%, about 0.1 to about 1.2%, about 0.1 to about 1%, about 0.1to about 0.8%, about 0.1 to about 0.6%, and about 0.1 to about 0.4%(w/w) of the composition.

In a composition having a volume based particle size (Dv50) of less thanabout 700 nm in size, the level of free surface stabilizer may forexample lie within the range of about 0.1 to about 2.9%, about 0.1 toabout 2.7%, about 0.1 to about 2.6%, about 0.1 to about 2.4%, about 0.1to about 2.2%, about 0.1 to about 2%, about 0.1 to about 1.8%, about 0.1to about 1.4%, about 0.1 to about 1.2%, about 0.1 to about 1%, about 0.1to about 0.8%, about 0.1 to about 0.6%, and about 0.1 to about 0.4%(w/w) of the composition.

In a composition having a volume based particle size (Dv50) of less thanabout 600 nm in size, the level of free surface stabilizer may forexample lie within the range of about 0.1 to about 2.9%, about 0.1 toabout 2.7%, about 0.1 to about 2.6%, about 0.1 to about 2.4%, about 0.1to about 2.2%, about 0.1 to about 2%, about 0.1 to about 1.8%, about 0.1to about 1.4%, about 0.1 to about 1.2%, about 0.1 to about 1%, about 0.1to about 0.8%, about 0.1 to about 0.6%, and about 0.1 to about 0.4%(w/w) of the composition.

In a composition having a volume based particle size (Dv50) of less thanabout 500 nm in size, the level of free surface stabilizer may forexample lie within the range of about 0.1 to about 2.9%, about 0.1 toabout 2.7%, about 0.1 to about 2.6%, about 0.1 to about 2.4%, about 0.1to about 2.2%, about 0.1 to about 2%, about 0.1 to about 1.8%, about 0.1to about 1.4%, about 0.1 to about 1.2%, about 0.1 to about 1%, about 0.1to about 0.8%, about 0.1 to about 0.6%, and about 0.1 to about 0.4%(w/w) of the composition.

In a composition having a volume based particle size (Dv50) of less thanabout 400 nm in size, the level of free surface stabilizer may forexample lie within the range of about 0.1 to about 2.9%, about 0.1 toabout 2.7%, about 0.1 to about 2.6%, about 0.1 to about 2.4%, about 0.1to about 2.2%, about 0.1 to about 2%, about 0.1 to about 1.8%, about 0.1to about 1.4%, about 0.1 to about 1.2%, about 0.1 to about 1%, about 0.1to about 0.8%, about 0.1 to about 0.6%, and about 0.1 to about 0.4%(w/w) of the composition.

In a composition having a volume based particle size (Dv50) of betweenabout 175 and about 350 nm in size, the level of free surface stabilizermay for example lie within the range of about 0.1 to about 2.9%, about0.1 to about 2.7%, about 0.1 to about 2.6%, about 0.1 to about 2.4%,about 0.1 to about 2.2%, about 0.1 to about 2%, about 0.1 to about 1.8%,about 0.1 to about 1.4%, about 0.1 to about 1.2%, about 0.1 to about 1%,about 0.1 to about 0.8%, about 0.1 to about 0.6%, and about 0.1 to about0.4% (w/w) of the composition.

In a composition having a volume based particle size (Dv50) of less thanabout 300 nm in size, the level of free surface stabilizer may forexample lie within the range of about 0.1 to about 2.9%, about 0.1 toabout 2.7%, about 0.1 to about 2.6%, about 0.1 to about 2.4%, about 0.1to about 2.2%, about 0.1 to about 2%, about 0.1 to about 1.8%, about 0.1to about 1.4%, about 0.1 to about 1.2%, about 0.1 to about 1%, about 0.1to about 0.8%, about 0.1 to about 0.6%, and about 0.1 to about 0.4%(w/w) of the composition.

In a composition having a volume based particle size (Dv50) of less thanabout 200 nm in size, the level of free surface stabilizer may forexample lie within the range of about 0.1 to about 2.9%, about 0.1 toabout 2.7%, about 0.1 to about 2.6%, about 0.1 to about 2.4%, about 0.1to about 2.2%, about 0.1 to about 2%, about 0.1 to about 1.8%, about 0.1to about 1.4%, about 0.1 to about 1.2%, about 0.1 to about 1%, about 0.1to about 0.8%, about 0.1 to about 0.6%, and about 0.1 to about 0.4%(w/w) of the composition.

In a composition having a volume based particle size (Dv50) of less thanabout 100 nm in size, the level of free surface stabilizer may forexample lie within the range of about 0.1 to about 2.9%, about 0.1 toabout 2.7%, about 0.1 to about 2.6%, about 0.1 to about 2.4%, about 0.1to about 2.2%, about 0.1 to about 2%, about 0.1 to about 1.8%, about 0.1to about 1.4%, about 0.1 to about 1.2%, about 0.1 to about 1%, about 0.1to about 0.8%, about 0.1 to about 0.6%, and about 0.1 to about 0.4%(w/w) of the composition.

The volume based particle size (Dv50) may be less than about 1000 nm,less than about 950 nm, less than about 900 nm, less than about 850 nm,less than about 800 nm, less than about 750 nm, less than about 700 nm,less than about 650 nm, less than about 600 nm, less than about 550 nm,less than about 500 nm, less than about 450 nm, less than about 400 nm,less than about 350 nm, less than about 300 nm, less than about 250 nm,less than about 200 nm, less than about 150 nm, less than about 100 nm,or less than about 50 nm. In a preferred embodiment, the volume basedparticle size (Dv50) of the aripiprazole prodrug particles is betweenabout 50 nm and 700 nm, more preferably between about 175 nm and about350 nm

In any of the compositions described above, where the Dv50 is less thanabout 900 nm, the Dv90 may be less than about 1700 nm, less than about1600 nm, less than about 1500 nm, less than about 1400 nm, less thanabout 1300 nm, less than about 1200 nm, less than about 1100 nm and lessthan about 1000 nm. The Dv10 may be less than about 850 nm, less thanabout 800 nm, less than about 700 nm, less than about 600 nm, less thanabout 500 nm, less than about 400 nm, less than about 300 nm, less thanabout 200 nm, and less than about 100 nm.

Where the Dv50 is less than about 800 nm, the Dv90 may be less thanabout 1600 nm, less than about 1500 nm, less than about 1400 nm, lessthan about 1300 nm, less than about 1200 nm, less than about 1100 nm,less than about 1000 nm and less than about 900 nm. The Dv10 may be lessthan about 750 nm, less than about 700 nm, less than about 600 nm, lessthan about 500 nm, less than about 400 nm, less than about 300 nm, lessthan about 200 nm, and less than about 100 nm.

Where the Dv50 is less than about 700 nm, the Dv90 may be less thanabout 1500 nm, less than about 1400 nm, less than about 1300 nm, lessthan about 1200 nm, less than about 1100 nm, less than about 1000 nm,less than about 900 nm and less than about 800 nm. The Dv10 may be lessthan about 650 nm, less than about 600 nm, less than about 500 nm, lessthan about 400 nm, less than about 300 nm, less than about 200 nm, andless than about 100 nm.

Where the Dv50 is less than about 600 nm, the Dv90 may be less thanabout 1500 nm, less than about 1400 nm, less than about 1300 nm, lessthan about 1200 nm, less than about 1100 nm, less than about 1000 nm,less than about 900 nm and less than about 800 nm, and less than about700 nm. The Dv10 may be less than about 550 nm, less than about 500 nm,less than about 400 nm, less than about 300 nm, less than about 200 nmand less than about 100 nm.

Where the Dv50 is less than about 500 nm, the Dv90 may be less thanabout 1500 nm, less than about 1400 nm, less than about 1300 nm, lessthan about 1200 nm, less than about 1100 nm, less than about 1000 nm,less than about 900 nm and less than about 800 nm, less than about 700nm, and less than about 600 nm. The Dv10 may be less than about 450 nm,less than about 400 nm, less than about 300 nm, less than about 200 nm,and less than about 100 nm.

Where the Dv50 is less than about 400 nm, the Dv90 may be less thanabout 1500 nm, less than about 1400 nm, less than about 1300 nm, lessthan about 1200 nm, less than about 1100 nm, less than about 1000 nm,less than about 900 nm and less than about 800 nm, less than about 700nm, less than about 600 nm, and less than about 500 nm. The Dv10 may beless than about 350 nm, less than about 300 nm, less than about 200 nmand less than about 100 nm.

Where the Dv50 is less than about 300 nm, the Dv90 may be less thanabout 1500 nm, less than about 1400 nm, less than about 1300 nm, lessthan about 1200 nm, less than about 1100 nm, less than about 1000 nm,less than about 900 nm and less than about 800 nm, less than about 700nm, less than about 600 nm, and less than about 500 nm, and less thanabout 400 nm. The Dv10 may be less than about 250 nm, less than about200 nm and less than about 100 nm.

Where the Dv50 is less than about 200 nm, the Dv90 may be less than 1500nm, less than about 1400 nm, less than about 1300 nm, less than about1200 nm, less than about 1100 nm, less than about 1000 nm, less thanabout 900 nm and less than about 800 nm, less than about 700 nm, lessthan about 600 nm, and less than about 500 nm, and less than about 400nm, and less than about 300 nm. The Dv10 may be less than about 150 nm,less than about 100 nm and less than about 50 nm.

Where the Dv50 is less than about 100 nm, the Dv90 may be less thanabout 1000 nm, less than about 900 nm and less than about 800 nm, lessthan about 700 nm, less than about 600 nm, and less than about 500 nm,and less than about 400 nm, and less than about 300 nm and less thanabout 200 nm. The Dv10 may be less than about 50 nm.

The composition may be formulated as a depot injection. This is thepreferred route of administration in order to ensure the long actingrelease of aripiprazole. Some depot compositions are designed to deliverthe drug over a period of several weeks or months. In this way the drugmay be delivered in a controlled fashion over a prolonged period. Wherethe composition is to be used as a lead in composition (in combinationwith a separate long acting injectable), presenting the composition as adepot injection offers a potential benefit over other routes ofadministration (e.g. oral lead in) because of the potential to simplifythe dosing regimen by reducing the frequency of the dosingadministration. In one embodiment, the depot composition of the presentinvention can be administered once in order to cover an entire lead inperiod which aids patient compliance, particularly useful in the contextof the patient population to which aripiprazole is aimed. In particular,aripiprazole is an atypical antipsychotic prescribed for treating, forexample, subjects with depression, schizophrenia and bipolar disorder.Such subjects may have difficulty complying with multi-step drug dosingschedules; the simplest dosing regimen is likely to obtain the highestpercentage of patient compliance.

Preferably, the depot injection is provided in an injection device suchas a pre-filled single or dual chambered syringe. This provides a muchsimpler and faster means of administering the composition without theneed for additional steps such as reconstituting a powder into adispersion etc.

The composition of the invention may be formulated as a powder forreconstitution in a liquid medium, wherein the population ofaripiprazole prodrug particles redisperse in the liquid medium such thatthe redispersed aripiprazole prodrug particles have a volume basedparticle size (Dv50) of less than about 1000 nm.

The composition of the invention may comprise a second population ofaripiprazole prodrug particles, the second population having a volumebased particle size (Dv50) of about 5000 nm or greater. Combining thecomposition of the present invention with a larger particle sizecomposition results in a bimodal or multi-modal composition which cancombine the advantages of fast onset of action and long actingtherapeutic effect. It was surprisingly discovered that a bimodal ormultimodal composition of aripiprazole prodrug did not experienceparticle size instability which commonly occurs with multi-modalcompositions of other active ingredients. This second population mayhave a volume based particle size (Dv50) range of between about 15 μmand about 25 μm.

The composition may comprise an additional atypical antipsychotic otherthan the aripiprazole prodrug used with the present invention.

The present application also relates to a method of treating a conditionin a mammal selected from schizophrenia, bipolar I disorder, majordepressive disorder (MDD), autistic disorder, agitation associated withschizophrenia or bipolar I disorder. The method comprises administeringa therapeutically effective amount of a composition as described hereinto a mammal in need thereof. Said method may include administering acomposition which is tailored to provide a therapeutic level ofaripiprazole over at least about 30 days (the lead-in period).Alternatively, the lead-in period may be at least about 15 days, atleast about 25 days, at least about 30 days, or any time point inbetween these values. This method simplifies the dosage regimeassociated with administering a lead in composition to a patient andeliminates the requirement to take an oral dose on a daily basis. Themethod may further include administering a composition of aripiprazoleprodrug having a volume based particle size (Dv50) of greater than about5000 nm, which can be carried out by co-administering the compositions(the respective compositions are administered at about the same time; asseparate compositions) or by administering the respective compositionstogether as a single composition. Alternatively, the method may includeadministering a composition which is tailored to maintain a therapeuticlevel of aripiprazole in the blood for no more than about 13 days andre-administering the composition at an appropriate time pointthereafter.

The present invention also relates to methods of improving initial invivo pharmacokinetic release profiles by providing a population ofaripiprazole prodrugs having a volume based particle distribution size(Dv50) between about 350 and about 175 nm as determined by lightscattering techniques, wherein the 17:1 ratio of said particles topolysorbate (most preferably polysorbate 20) achieves a therapeuticconcentration of aripiprazole in less than seven days. In a preferredembodiment the population of aripiprazole prodrugs has a volume basedparticle distribution size (Dv50) of less than about 400 nm, less thanabout 300 nm, less than about 200 nm and/or less than about 100 nm. In afurther preferred embodiment, the ratio of said particles to polysorbate20 achieves a therapeutic concentration of aripiprazole in less thanabout 72 hours, about 48 hours and/or about 24 hours.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a prior art graphical representation of an induction periodexperienced with a 20 μm aripiprazole lauroxil formulation.

FIG. 2 is a plot of the mean plasma and blood concentrations forFormulations 1, 2 (comparator), 3 (comparator) and 4 as measured in vivoin rodent subjects over the various time points and as discussed inExamples 1 and 2.

FIG. 3 is a plot of the mean blood concentrations as measured in vivo inrodent subjects for Formulations 5 and 6 as discussed in Example 3.

FIG. 4 is a plot of the mean aripiprazole concentrations as measured invivo in rodent subjects for Formulations 7, 8, 9 and 10 (comparator)discussed in Example 4.

FIG. 5 is a plot of mean aripiprazole concentrations as measured in vivoin dog subjects for Formulations 11, 12 and 13 as compared with a 20,000nm formulation, which is discussed in Example 5.

FIG. 6 is a plot of mean aripiprazole concentrations as measured in vivoin dog subjects for Formulations 14 to 17 of Example 6.

FIG. 7 is a plot of the mean aripiprazole concentrations as measured invivo in dog subjects for Formulations 18, 20 and 23 of Example 7.

FIG. 8 is a plot of mean aripiprazole concentrations as measured in vivoin dog subjects for Formulations 19, 20 and 21 of Example 7.

FIG. 9 is a plot of the mean aripiprazole concentrations as measured invivo in dog subjects for Formulations 25, 26 and 27 of Example 8.

FIG. 10 is a plot of the mean aripiprazole concentrations as measured invivo in dog subjects for Formulations 25 to 27 of Example 8.

FIG. 11 is a plot of the mean aripiprazole lauroxil concentrations asmeasured in vivo in dog subjects for Formulations 25, 28 and 29 asdiscussed in Example 8.

FIG. 12 is a plot of mean aripiprazole concentrations as measured invivo in dog subjects for Formulations 25, 28 and 29 (illustrating theeffect of the active to surface stabilizer ratio on measuredaripiprazole levels) as discussed in Example 8.

FIG. 13 is a plot of the mean aripiprazole concentrations as measured invivo in dog subjects for Formulations 27 and 30 (illustrating the effectof the active to surface stabilizer ratio on aripiprazole levels), asdiscussed in Example 8.

FIG. 14 is a plot of the mean aripiprazole lauroxil concentrations asmeasured in vivo in dog subjects for Formulations 25 and 30(illustrating the effect of the active to surface stabilizer ratio onaripiprazole levels), as discussed in Example 8.

FIG. 15 is a plot of the mean aripiprazole concentrations as measured invivo in a dog model for Formulations 25 and 30 of Example 8(illustrating the effect of the active to surface stabilizer ratio onaripiprazole levels).

FIG. 16: depicts the AUC of aripiprazole lauroxil for formulations 25,28 and 29 (formulations at fixed surface area and increasing polysorbate20 concentration) from dog study.

FIG. 17: depicts the AUC of aripiprazole for formulations 25, 28 and 29(formulations at fixed surface area and increasing polysorbate 20concentration) from dog study.

FIG. 18A depicts the amount of free polysorbate 20 for formulations 25,28 and 29 (formulations at fixed surface area and increasing polysorbate20 concentration) determined by HPLC, and FIG. 18B depicts the amount ofdissolved aripiprazole lauroxil for formulations 25, 28 and 29(formulations at fixed surface area and increasing polysorbate 20concentration) determined by HPLC.

FIG. 19A depicts the AUC of aripiprazole lauroxil for formulations 27and 30 (formulations at fixed surface area and increasing polysorbate 20concentration) from dog study, and FIG. 19B depicts the AUC ofaripiprazole for formulations 27 and 30 (formulations at fixed surfacearea and increasing polysorbate 20 concentration) from dog study.

FIG. 20A depicts the amount of free polysorbate 20 for formulations 27and 30 (formulations at fixed surface area and increasing polysorbate 20concentration) determined by HPLC, and FIG. 20B depicts the amount ofdissolved aripiprazole lauroxil for formulations 27 and 30 (formulationsat fixed surface area and increasing polysorbate 20 concentration)determined by HPLC.

FIG. 21A depicts the amount of free polysorbate 20 for formulations 25,26 and 30 (formulations at fixed surface area and increasing polysorbate20 concentration) determined by HPLC, and FIG. 21B depicts the amount ofdissolved aripiprazole lauroxil for formulations 25, 26 and 30(formulations at fixed surface area and increasing polysorbate 20concentration) determined by HPLC.

FIG. 22: depicts the AUC of aripiprazole lauroxil and aripiprazole forformulations 25, 26 and 30 (formulations at fixed surface area andincreasing polysorbate 20 concentration) from dog study.

FIG. 23: is a plot of the viscosity verses shear curve as measured forFormulation 31 of Example 9.

FIG. 24: is a plot of particle size over time as measured forFormulation 31 of Example 9.

FIG. 25: depicts the mean aripiprazole concentrations as measured invivo in a rodent model for Formulations X and Y of Example 12.

FIG. 26: depicts the microscope images of formulations X and Y dilutedin phosphate buffer saline of Example 12.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described herein using several definitions, asset forth below and throughout the application.

As used herein, “about” will be understood by persons of ordinary skillin the art and will vary to some extent on the context in which it isused. If there are uses of the term which are not clear to persons ofordinary skill in the art given the context in which it is used, “about”will mean up to plus or minus 10% of the particular term.

A “long acting injectable” or “depot” injection is an injectablecomposition (usually subcutaneous or intramuscular) which upon injectionforms a reservoir of the drug substance within the body of the subjectfrom which the drug is slowly distributed into systemic circulation. Inthis way the drug may be delivered in a controlled fashion over aprolonged period. As defined herein, a depot injection releases thearipiprazole prodrug over an extended period of time, at least about 24hours and preferably about 1 week or more.

The term “injection site reaction” as used herein refers to any adversephysiological response around the site of needle entry after injection.

The term “lead in composition” as used herein refers to a formulation ofan active agent which reduces or eliminates the “lead in” period asreferenced below. In other words, a lead in composition acts to increasethe active agent levels during the lead in period over and above thelevel of what would be observed in the absence of the lead incomposition. This may also be referred to as a loading dose.

The term “lead in” or “lead in period” as used herein refers to a periodof time following administration of an active agent to a subject beforethe level of active agent in systemic circulation reaches atherapeutically effective amount for the mammalian subject to which itis dosed.

The term “particle size” or “volume based particle size” or “volumebased particle size distribution” as used herein is equivalent to andalso referred to as the Dv50 or D50 and means that at least about 50% ofthe aripiprazole prodrug particles have a diameter of less than the sizespecified. The aforementioned terms are used interchangeably herein. Forexample a volume based particle size (Dv50) of less than 1000 nm, meansthat 50% of the particle population has a diameter of less than 1000 nmwhen measured by static or dynamic light scattering techniques known tothose skilled in the art. Since the particles of the present inventiontend to be irregular in shape, an approximation of the particle size ismade on the basis of the volume based particle size, which specifies thediameter of the sphere that has same volume as a given particle. Unlessotherwise specified, all particle sizes are specified in terms of volumebased measurements and are measured by laser lightscattering/diffraction. Particle sizes are then determined based on Miescattering theory. More specifically, unless otherwise specified, volumebased particle size (Dv50) is determined using a Horiba LA-950 standardmodel laser particle size analyser. Deionized water or water with asmall quantity (for example 0.1% w/w) of surface stabilizer (for examplepolysorbate 20) is used as the sizing medium unless otherwise specified.The terms “D90” and “D10” mean that, respectively at least about 90% and10% of the aripiprazole prodrug particles have a diameter of less thanthe size specified. These may also be referred to as “Dv90” and “Dv10”respectively, and these terms are used interchangeably herein.

The term “mean particle size” is essentially the same as “volume meandiameter” and in the present application this is defined in the samemanner as defined in the Horiba Scientific brochure, “A guidebook toparticle size analysis” (2012), available from Horiba's website,www.horiba.com. The calculation is expressed by conceptualizing ahistogram table showing the upper and lower limits of n size channelsalong with the percent within each channel. The Di value for eachchannel is the geometric mean, the square root of upper×lower diameters.For the numerator take the geometric Di to the fourth power×the percentin that channel, summed over all channels. For the denominator take thegeometric Di to the third power×the percent in that channel, summed overall channels. The volume mean diameter is referred to by several namesincluding D[4,3].

${D\left\lbrack {4,3} \right\rbrack} = \frac{\sum\limits_{1}^{n}D_{{}_{}^{}{}_{}^{}}^{4}}{\sum\limits_{1}^{n}D_{{}_{}^{}{}_{}^{}}^{3}}$

The skilled person will appreciate that particle size can also bedetermined by other suitable measurement means, such as by volume,number, etc.), and can be measured by, for example, sedimentation flowfractionation, dynamic light scattering, disk centrifugation, and othertechniques known in the art. A full description of dynamic and staticlight scattering techniques is provided from pages 121-131 of“Nanoparticle technology for drug delivery” by Ram B. Gupta and Uday B.Kompella, published by Taylor & Franceis Group (ISBN 1-57444-857-9) andpages 569-580 of “Pharmaceutics, the science of dosage form design”edited by Michael E. Aulton and published by Churchill Livingstone(ISBN: 0-443-03643-8). It is intended that the definition of particlesize as specified in the claims should cover measurements using anytechnique used in the art for particle size characterisation.

A “prodrug” is a therapeutically inactive molecule which can bephysiologically metabolized into an active pharmaceutical ingredient.The terms “drug” or “active agent,” when used herein, typically refersto aripiprazole (the metabolite) but may, if clearly indicated by itscontext, refer to another drug.

A “size stable” composition is a composition that exhibits noflocculation or particle agglomeration visible to the naked eye at leastabout 15 minutes, and preferably at least about two days or longer afterpreparation. Preferably, a “size stable” composition is a compositionwhere the volume based particle size (Dv50) and/or mean particle sizedoes not increase by any more than about 400 nm when the composition isstored at about 20° C. for a period of about 24 hours. More preferably,a “size stable” composition is where the volume based particle size(Dv50) and/or mean particle size does not increase by any more thanabout 400 nm when the composition is stored at about 40° C. for a periodof about 6 months. Most preferably, a “size stable” composition is wherethe volume based particle size (Dv50) and/or mean particle size does notincrease by any more than about 100 nm when the composition is stored atabout 40° C. for a period of about 6 months.

As used herein, the term “subject” is used to mean an animal, preferablya mammal, including a human or non-human. The terms patient and subjectmay be used interchangeably.

The term “therapeutically effective amount” refers to the minimum bloodconcentration of aripiprazole in order to have a therapeutic effect.This may vary depending on the type of subject. In the case of humans,the US Food and Drug Administration summary basis of approval documentfor Abilify Maintena defines this value as 94 ng/mL. Unless otherwiseindicated this value in relation to humans is defined herein as at leastabout 34-about 50 ng/mL, and preferably about 94 ng/mL.

The terms “treatment,” “therapy,” “therapeutic” and the like, as usedherein, encompass any course of medical intervention aimed at apathologic condition, and includes not only permanent cure of a disease,but prevention of disease, control or even steps taken to mitigate adisease or disease symptoms.

Relationship between free surface stabilizer and initial in-vivo release

The composition of the present invention comprises stabilizedaripiprazole particles (particles having a surface stabilizer adsorbedto the surface thereof to mitigate against drug particle aggregationand/or crystal growth) having a volume based particle size (Dv50) ofless than about 1000 nm and a free component of surface stabilizer. Itwas surprisingly discovered that the combination of these features i.e.,stabilized aripiprazole particle size to free surface stabilizer ratioresults in a significantly enhanced pharmacokinetic profile incomparison to aripiprazole compositions which do not include thesefeatures.

By appropriate selection of the stabilized aripiprazole particle sizeand the level of free surface stabilizer, the composition of the presentinvention can be tailored to achieve an in vivo release profile based ona given dosage application. For example, appropriate selection of thestabilized aripiprazole particle size and level of free surfacestabilizer can provide a significant modulation of the pharmacokineticprofile by providing a shorter time to T_(max) and onset time (i.e.period of time after administration before the active reaches atherapeutic concentration in the blood). In order to ensure thatsufficient free component of surface stabilizer will be present in thecomposition of the present invention, a sufficient quantity (in excessof that required to stabilize particles) of surface stabilizer must beadded to the composition. The total amount of surface stabilizer addedmust take account the aripiprazole prodrug particle size. It is thecombination of features i.e., stabilized aripiprazole particle size tofree stabilizer ratio that modulates the desired rate of aripiprazolerelease as described in FIGS. 16-22 and Table 13 of Example 8.

As defined herein, a lead in pharmacokinetic profile may be defined asany in vivo pharmacokinetic release profile in human or mammaliansubjects which achieves a therapeutic concentration in the blood of lessthan about 1 week, preferably less than about 72 hours, more preferablyless than about 48 hours and more preferably less than about 24 hours,and which maintains a therapeutic level for at least about 1 week,preferably about 2 weeks and more preferably about 3 weeks.

Without being bound to theory, a possible mechanism by which the freesurface stabilizer modifies the in vivo pharmacokinetic release profileof the composition described herein is through assisting or increasingthe solubility of the aripiprazole prodrug. One mechanism by which itmay do so is by forming micelles containing solubilized drug. Thisensures that a greater proportion of the prodrug can be solubilised in agiven time period. Another possible mechanism of action is that afterthe prodrug composition is administered (e.g. by intramuscular depotinjection), particles have a tendency to aggregate in the muscle tissueand the presence of a free surface stabilizer component reduces, slowsor prevents such aggregation from occurring, thus speeding updistribution and ultimately absorption.

It is particularly preferred that the volume based particle size (Dv50)of the aripiprazole prodrug composition of the present invention bewithin the range of about 50 nm to about 750 nm, and that the ratio ofdrug to surface stabilizer in the composition lies within the range ofabout 17:1 to about 26:1. Preferably, the volume based particle size(Dv50) of the aripiprazole prodrug composition of the present inventionbe within the range of about 350 nm and about 175 nm. Even morepreferably, compositions provide a free surface stabilizer amount withinthe range of about 1% to about 1.6% (w/w).

The composition of the present invention may be tailored as a lead incomposition to a conventional long acting antipsychotic formulation, inorder to address any delay in onset which may occur with suchformulations. The present composition can be used as a lead in inconjunction with any long acting atypical antipsychotic (for exampleAbilify Maintena®) to address any delay in onset experienced with theseformulations. The preferred use of the present invention is as a lead infor the aripiprazole prodrugs as described herein.

Compositions of the Present Invention

The composition of the present invention comprises certain aripiprazoleprodrugs which are described in U.S. Pat. No. 8,431,576, which isspecifically incorporated by reference. In particular, the aripiprazoleprodrug referenced in relation to the present invention has the generalformula:

where n is any whole number greater than or equal to 0 and less than 20.In the preferred embodiments discussed below, n is equal to 4 or 10.

One such compound is aripiprazole hexanoate (in this case n=4), the USANterm for which is aripiprazole cavoxil. Aripirazole cavoxil is theN-hexanoyloxymethyl prodrug of aripiprazole and has the followingstructure.

The above compound may be described by the chemical name(7-(4-(4-(2,3-Dichlorophenyl)piperazin-1-yl)butoxy)-2-oxo-3,4-dihydroquinolin-1(2H)yl)methyl hexanoate and the molecular formula C₃₀H₃₉Cl₂N₃O₄. Themolecule has the CAS registry number 1259305-26-4.

Another such compound is aripiprazole laurate (in this case n=10). TheUSAN term for which is aripiprazole lauroxil. Aripirazole lauroxil isthe N-lauroyloxymethyl prodrug of aripiprazole and has the followingstructure:

This above compound can be described by the chemical name Dodecanoicacid,[7-[4-[4-(2,3-dichlorophenyl)-1-piperazinyl]butoxy]-3,4-dihydro-2-oxo-1(2H)-quinolinyl]methylester and the molecular formula C₃₆H₅₁Cl₂N₃O₄. The molecule has the CASregistry number 1259305-29-7.

Aripiprazole lauroxil is a long acting injectable indicated forschizophrenia developed by Alkermes Pharma Ireland Limited in the formof a microcrystalline suspension having a particle size in the order ofabout 20 μm.

Dosage Forms and Administration of the Present Invention

The composition of the present invention may also be formulated as adosage form to be administered about once a week. A once-weekly dosageregimen according to the present invention can be provided in the formof an intramuscular depot injection, which can be provided as are-constitutable powder or provided in an injection device such as apre-filled syringe.

A once-weekly dosage form may be defined as a dosage that provides an invivo pharmacokinetic profile in human or mammalian subjectscharacterised by achieving a therapeutic concentration in the blood inless than about 72 hours and which maintains a therapeutic level for aminimum of about 5 days and a maximum of about 13 days. Preferably, aonce weekly dosage form when dosed in a mammalian subject reaches atherapeutic concentration in the blood of the subject in less than about36 hours and maintains a therapeutic level in the blood of the subjectfor a minimum of about 5 days and a maximum of about 9 days.

The composition may also be formulated for administration once every twoweeks or once every three weeks. An example of such a composition wouldreach a therapeutic concentration in the blood of the subject in lessthan about 7 days, and would maintain a concentration of aripiprazolewhich is above the therapeutic concentration for a minimum of about 14days, preferably about 21 days and a maximum of about 28 days. Such acomposition could provide an alternative dosing regimen which provides astructure for regular visits to a healthcare professional, but is lessstringent and inconvenient for the patient than a once weekly dosingregimen.

The composition of the present invention may also be formulated as along acting composition, which can maintain a therapeutic level ofactive in the blood for at least about 1 week and up to about 1 month.Accordingly the composition of the present invention can be tailored toa release profile serving as both a lead in and a long acting injectablein its own right.

The composition may also be formulated for administration once every twoweeks or once every three weeks. An example of such a composition wouldreach a therapeutic concentration in the blood of the subject in lessthan about 7 days, and would maintain a concentration of aripiprazolewhich is above the therapeutic concentration for a minimum of about 14days, preferably about 21 days and a maximum of about 28 days. Such acomposition could provide an alternative dosing regimen which provides astructure for regular visits to a healthcare professional, but is lessstringent and inconvenient for the patient than a once weekly dosingregimen.

The composition of the present invention may also be formulated forconcurrent administration with an oral atypical antipsychotic,preferably Aripiprazole. Aripiprazole is commercially available in theUnited States under the brand name Abilify® (Ability is a registeredtrademark of Otsuka Pharmaceutical Co., Ltd.), manufactured/marketed byBristol-Myers Squibb of Princeton, N.J. and marketed by Otsuka AmericaPharmaceutical, Inc. Aripiprazole is available in tablet form, orallydisintegrating tablet form and as an oral solution. In particular, theoral antipsychotic is dosed at 10 mg, 20 mg, 30 mg, 40 mg, 50 mg, 60 mg,70 mg, 80 mg, 90 mg and/or 100 mg. Preferably, the oral antipsychotic isdosed at 30 mgs.

The composition of the present invention, in addition to having apopulation of particles with a volume based particle size (Dv50) of lessthan 1000 nm may also include a second larger particle size populationof aripiprazole prodrug particles having a volume based particle size(Dv50) of about 5000 nm or greater. For example, a population ofaripiprazole prodrug particles having a volume based particle size(Dv50) of 20 μm can be included in the composition of the presentinvention in order to provide the characteristics of a lead incomposition as described earlier with a long acting release profile in asingle composition.

This therefore leads to a simplified dosage regime since the lead incomponent which provides fast onset and therapeutic levels ofaripiprazole in the blood thereafter for the duration of the lead inperiod and a long acting component, which reaches a therapeutic level inthe blood after the lead in period and maintains the therapeutic levelover a period of at least about 30 days. This ensures that a singlecomposition maintains therapeutic concentration in the blood for aperiod of at least about 1 to about 30 days. The requirement for aseparate lead in and long acting injection is therefore avoided, whichhas the direct consequence of simplifying the dosage regime andimproving patient compliance.

It is considered surprising that a mixed population of particles can beproduced as a stable composition at all. The present inventors haveobserved in relation to mixed populations of other active ingredientsthat where at least one of the populations has a small (less than about2000 nm) volume based particle size (Dv50), both populations have atendency to experience a change in particle size due to the effects ofOstwald ripening. Ostwald ripening is a phenomenon observed in smallparticle populations where multiple particle sizes are present.Typically, smaller particles dissolve then crystallise causing thelarger particles present to grow. The phenomenon is relatively commonwith a large number of active agents, particularly active agents havinga high solubility. Surprisingly, the incidence of Ostwald ripening inmixed populations of aripiprazole prodrug according to the presentinvention was observed to be very low when measured over a period ofabout 1 month. A possible explanation for this might lie in the factthat the present active agent has a particularly low aqueous solubility,meaning that particles of the active agent have a lower tendency todissolve and recrystallize. This may be a unique property of hydrophobicmaterials: that the low surface free energies prevent particle sizegrowth from occurring.

In another embodiment, the composition of the present invention, inaddition to having an aripiprazole prodrug population of particle sizeless than 1000 nm, may include a second aripiprazole prodrug particlepopulation having a volume based particle size (Dv50) which is less than1000 nm in size, and at least about 100 nm, at least about 200 nm, atleast about 300 nm, at least about 400 nm, at least about 500 nm, atleast about 600 nm, at least about 700 nm, at least about 800 nm or atleast about 900 nm greater than the Dv50 of the (first) aripiprazoleprodrug population.

In another embodiment, the composition of the present invention may bedelivered in a dual chamber syringe, in which one of the chambers isprovided with a second aripiprazole prodrug composition having adifferent particle size. For example, the second aripiprazolecomposition may have a particle size which is also less than 1000 nm,between about 1000 and about 5000 nm or greater than about 5000 nm. Bothcompositions are thereby stored separately.

The composition of the present invention may be presented in the form ofa particulate dispersion. The composition comprises a dispersion mediumin which the population of aripiprazole prodrug particles is dispersed,and in which the free component of the surface stabilizer is dissolvedor otherwise dispersed.

The composition of the present invention may additionally be provided asa dispersion (as described above). Such a dispersion may for example beprovided in an injection device such as a pre-filled syringe. However,it should be understood that an injection device can include any devicecapable of delivering an injection which may be used with the presentinvention. For example, the compositions of the present invention mayalso be administered using an auto-injector device. Alternatively, thecompositions of the present invention may be delivered using a needlesssyringe, or a dual-chamber syringe.

The composition of the present invention may be formulated as a powderfor reconstitution in a liquid medium. A significant feature of thepresent invention in this regard is that the population of aripiprazoleprodrug particles redisperse when reconstituted in a liquid medium suchthat the redispersed aripiprazole prodrug particles have a volume basedparticle size (Dv50) of less than 1000 nm.

One of ordinary skill will appreciate that effective amounts ofaripiprazole prodrug can be determined empirically. Actual dosage levelsof aripiprazole prodrug in the composition of the invention may bevaried to obtain an amount of an aripiprazole prodrug that is effectiveto obtain a desired therapeutic response for a particular compositionand method of administration. The selected dosage level thereforedepends upon the desired therapeutic effect, the route ofadministration, the potency of aripiprazole prodrug, the desiredduration of treatment, and other factors. Dosage unit compositions maycontain such amounts of such submultiples thereof as may be used to makeup the daily dose. It will be understood, however, that the specificdose level for any particular patient will depend upon a variety offactors: the type and degree of the cellular or physiological responseto be achieved; activity of the specific agent or composition employed;the specific agents or composition employed; the age, body weight,general health, sex, and diet of the patient; the time ofadministration, route of administration, and rate of excretion of theagent; the duration of the treatment; drugs used in combination orcoincidental with the specific agent; and like factors well known in themedical arts.

Surface Stabilizers

The composition of the invention comprises at least one surfacestabilizer. However, combinations of more than one surface stabilizerhave been found to be useful and can be used in the invention. Where aplurality of surface stabilizers is used there may be a primary surfacestabilizer that is present in greater concentration than the other(secondary) surface stabilizer(s).

Without being restricted to theory, it is believed that the surfacestabilizer functions by forming a steric barrier or an electrostaticbarrier around the drug particles, thereby providing enough physicalseparation of the particles to prevent particle aggregation. Severalcompounds are known to possess the properties of forming such a stericor electrostatic barrier when applied to small particles. It istherefore plausible that any one of these substances could function as asurface stabilizer in the context of the present invention and thereforefall within the scope of the invention. The term surface stabilizer maybe used interchangeably with the term surface modifier.

Useful surface stabilizers which can be employed in the inventioninclude, but are not limited to, known organic and inorganicpharmaceutical excipients. Such excipients include various polymers, lowmolecular weight oligomers, natural products, and surfactants. Exemplarysurface stabilizers include non-ionic and ionic (e.g., anionic,cationic, and zwitterionic) surface stabilizers. Without wishing to bebound by any particular theory, it is believed that polymeric materialsadhering to a particle surface can present a steric barrier preventingparticle aggregation, while in the case of ionic surface stabilizers thestabilizing action may be attributed to electrostatic interactions.

Particularly preferred surface stabilizers for use with the presentinvention are polysorbate surfactants also referred to as polysorbatesor polyoxyethylene sorbitan fatty acid esters. Examples include thoseavailable under the Tween® tradename (a registered trademark of Uniqema,a business unit of ICI Americas Inc.), such as Tween® 20(polyoxyethylene 20 sorbitan monolaurate) also referred to aspolysorbate 20 or PS20 herein, Tween® 40 (polyoxyethylene 20 sorbitanpalmitate), also referred to as polysorbate 40 or PS40 herein or Tween®80 (polyoxyethylene 20 sorbitan monooleate), also referred to aspolysorbate 80 or PS80 herein. Polysorbates are amphiphilic, nonionicsurfactants composed of a hydrophilic head group (sorbitanpolyoxyethylene) linked by an ester bond to a hydrophobic tail group.The various grades differ in the length of this tail group, for examplePS20 (laurate, C12), PS40 (palmitate, C16), PS80 (oleate, C18).

Other preferred surface stabilizers for use with the present inventioninclude low molecular weight povidones, lecithin, DSPG(1,2-Distearoyl-sn-glycero-3-phospho-rac-(1-glycerol)), DOSS (dioctylsodium sulfosuccinate, or docusate sodium), methyl and propyl parabens,sorbitan monolaurate, also referred to as SML, available under the tradename Span® 20, a registered trademark of Croda International PLC,carboxymethyl cellulose, hydroxypropylcellulose, also referred to as HPCand including examples such as HPC-SL a low viscosity grade which has aviscosity of 2.0 to 2.9 mPa·s in aqueous 2% w/v solution at 20° C.(available from Nippon Soda Co Ltd, Japan), sodium deoxycholate,akylsaccharides. Also preferred are block copolymers based on ethyleneoxide and propylene oxide, also known as poloxamers and sold for exampleunder the trade names Pluronic® and Lutrol®, registered trademarks ofthe BASF Corporation and Synperonic, a registered trademark of CrodaInternational PLC. Examples include poloxamer 407 (Lutrol® F127),poloxamer 188 (Lutrol® F68/Pluronic® F68) or Poloxamer 338 (Lutrol®F108/Pluronic® F108). Polaxamers are amphiphilic, nonionic tri-blockcopolymers consisting of a central hydrophobic poly(propylene oxide)(PPO) block with terminal hydrophilic poly(ethylene oxide) (PEO) blocks.The various grades differ in the length of these blocks and proportionof the hydrophilic content. Poloxamer 188 is (18×10≈) 1800 g/mol and an(8×10≈) 80% of the total is polyoxyethylene; (PEO₈₀-PPO₂₇-PEO₈₀).Poloxamer 338 is (33×1000≈) 3300 g/mol and an (8×10≈) 80% of the totalis polyoxyethylene; (PEO₁₃₂-PPO₅₀-PEO₁₃₂). It is also envisaged to useonly the individual components which make up these block co-polymers,for example in the case of Pluronic F108, such individual components arePolyoxyethylene and polyoxypropylene glycol. It is particularlypreferred to use the aforementioned individual components given theirapproval status. Other preferred stabilizers include TPGS (d-alphatocopheryl polyethylene glycol 1000 succinate), gelatin and albumin,lysozyme and cyclodextrins (for e.g. betahydroxcyclodextrin). Alsouseful are gel forming polymers such as ReGel® (thermosettingbiodegradable gel developed by British Technology Group)(ReGel is aregistered trademark of protherics salt lake city, inc.). Particularlypreferred surface stabilizers for use with the present invention arethose which are approved by any regulatory authority for the preferredroute of administration, intramuscular use.

Of the aforementioned, the following are particularly preferred as theywould generally be considered to be more acceptable for intramuscularuse: polysorbate surfactants such as Polysorbate 80, Polysorbate 40 andPolysorbate 20, low molecular weight povidones, lecithin, DSPG, andsorbitan monolaurate.

Other useful surface stabilizers include copolymers of vinylpyrrolidoneand vinyl acetate or copovidone (e.g., Plasdone® S630, which is a randomcopolymer of vinyl acetate and vinyl pyrrolidone available from ISPTechnologies, Inc (USA)); hydroxypropylmethylcellulose (HPMC, such asPharmacoat® 603 available from Shin-Etsu Chemical Co Ltd, Japan); apolyvinylpyrrolidone (PVP), such as those available from ISP Corp (NewJersey, USA) under the Plasdone® trade name, e.g. Plasdone® C29/32(which is equivalent to BASF PVP K29/32), Plasdone® C-30, Plasdone® C17(equivalent to BASF PVP K-17) and Plasdone® C12 (equivalent to povidoneK12); deoxycholic acid sodium salt, sodium lauryl sulphate (SLS alsoknown as sodium dodecyl sulphate or SDS), benzalkonium chloride (alsoknown as alkyldimethylbenzylammonium chloride), lecithin, distearylpalmitate glyceryl or a combination thereof. Other preferred surfacestabilizers include albumin, lysozyme, gelatin, macrogol 15hydroxystearate (available for example from BASF AG under the trade nameSolutol® 15), tyloxapol and polyethoxylated castor oil (available forexample from BASF AG under the trade name Cremophor® EL), PEG-40 Castoroil (Cremophor® RH 40, a registered trademark of the BASF group),(2-Hydroxypropyl)-β-cyclodextrin, Polyethylene glycol tert-octylphenylether (Triton X-100™, a trademark of The Dow Chemical Company),Polyethylene glycol (15)-hydroxystearate (Solutol® HS 15, a registeredtrademark of the BASF group), sulfobutyl ether β-cyclodextrin.

The surface stabilizers are commercially available and/or can beprepared by techniques known in the art. Most of these surfacestabilizers are known pharmaceutical excipients and are described indetail in the Handbook of Pharmaceutical Excipients, published jointlyby the American Pharmaceutical Association and The PharmaceuticalSociety of Great Britain (R. C. Rowe et al (ed.) 5^(th) Edition, ThePharmaceutical Press, 2006), specifically incorporated by reference.

Excipients

The composition of the present invention may further comprise one ormore non-toxic physiologically acceptable carriers, adjuvants, orvehicles, collectively referred to as carriers. The composition can beformulated for administration via any pharmaceutically acceptable means,including but not limited to, parental injection (e.g. intramuscular, orsubcutaneous). The small size of the aripiprazole prodrug particles(i.e. less than 1000 nm) makes the composition of the inventionparticularly advantageous for parenteral formulations.

The composition of the invention may include a chelating agent such assodium citrate or sodium phosphate monobasic dihydrate (NaH₂PO₄ 2H₂O) orSodium phosphate dibasic anhydrous (NaH₂PO₄). Chelating agents bind withmetal ion impurities introduced during the milling process thuspreventing the formation of aldehydes.

The present composition may also include a buffer in order to raise thepH of the dispersion medium. Certain surface stabilizers, in particularPolysorbate 20 may be susceptible to oxidation. If after milling, thepolysorbate 20 in composition oxidises, this may have the effect oflowering the overall pH of the dispersion medium. The drug thereaftermay become more soluble in a medium of lower pH, possibly leading togrowth in particle size due to processes such as Oswald ripeningoccurring. A buffer may therefore be included to counter any drop in pHand prevent this effect from occurring. Buffers which may be used withthe composition of the present invention include sodium citrate orsodium phosphate monobasic dihydrate (NaH₂PO₄ 2H₂O) or Sodium phosphatedibasic anhydrous (NaH₂PO₄).

The present composition may also include an antioxidant to prevent theoxidation of the surface stabilizer or any other constituent. Citricacid may be used an effective antioxidant.

The composition of the invention may also comprise a tonicity agent suchas saline, sugars or polyols.

As described above, the composition of the present invention may beformulated as a dispersion, in which case the particles of the presentinvention are dispersed within a dispersion medium. The dispersionmedium may be comprised of water and/or any of the excipients describedabove. Oils or other non-aqueous media may be used where compatible withthe aripiprazole prodrug. Preferably, the dispersion medium is water oran aqueous based medium.

Alternatively, the composition of the present invention may be presentedas particles in a dry form to be dispersed in a dispersion medium priorto administration. In such embodiments, the composition preferablycomprises one or more of the above mentioned excipients and isreconstituted in water prior to administration.

Methods of Preparing the Aripiprazole Prodrug Composition of theInvention

The present invention further relates to a method of preparing anaripiprazole prodrug composition according to the present invention.

The method comprises the step of (a) calculating a quantity of at leastone stabilizer to be added to the composition in order to ensure thatboth an adsorbed component and a free component of the stabilizer arepresent in the composition. This calculation may be done for exampleusing methods for approximating the quantity of free surface stabilizerdescribed herein. The method further includes (b) producing a populationof aripiprazole prodrug particles having a volume based particle size(Dv50) of less than 1000 nm as determined by light scattering. This maybe performed using any of the methods described below for producingsmall particles. The preferred method is milling. The method furtherincludes (c) combining the quantity of surface stabilizer with thepopulation of aripiprazole prodrug particles, such that the adsorbedcomponent of the surface stabilizer is adsorbed on the surface of thearipiprazole prodrug particles. Adsorption of the surface stabilizer tothe particles of aripiprazole prodrug may be attained by contacting theparticles with the at least one surface stabilizer for a time and underconditions sufficient to provide a composition comprising particles ofaripiprazole prodrug having a volume based particle size (Dv50) of lessthan 1000 nm. Step (b) and step (c) may be performed simultaneously bymilling the aripiprazole prodrug with the stabilizer present, which isdescribed in detail below and in the examples. The method may furthercomprise the step of (d) retaining a sample of the composition fortesting the quantity of the free component of surface stabilizer, (e)separating the aripiprazole lauroxil particles and the surfacestabilizer adsorbed thereto from the dispersion medium in the sample toform a supernatant, and (f) measuring the quantity of surface stabilizerin the supernatant using a high performance liquid chromatography (HPLC)apparatus in order to verify that the free component of stabilizer isindeed present in the composition. The method may further comprise thestep of (g) combining the aripiprazole prodrug particles and the surfacestabilizer with a dispersion medium to form a dispersed aripiprazoleprodrug composition. Further possible steps include (h) combining thearipiprazole prodrug particles with an additional population ofaripiprazole prodrug particles having a volume based particle size(Dv50) at least about 100 nm greater in size and (i) filling thedispersed aripiprazole prodrug composition into an injection device (forexample prefilled syringe, auto-injector, needleless syringe or dualchambered syringe. If a dual chambered syringe is used, the method caninclude the additional step of (g) filling the aripiprazole prodrugcomposition into one chamber of the dual chambered syringe, and fillingthe other chamber of the dual chamber syringe with a second composition.The second composition may be a second aripiprazole prodrug composition,having a different volume based particle size (Dv50) or could be annon-aripiprazole active ingredient, for example an atypicalantipsychotic.

The composition of the present invention can be made using, for example,milling or attrition (including but not limited to wet milling),homogenization, precipitation, freezing, template emulsion techniques,supercritical fluid techniques, nano-electrospray techniques, or anycombination thereof. Exemplary methods of making nanoparticulatecompositions are described in the '684 patent. Methods of makingnanoparticulate compositions are also described in U.S. Pat. No.5,518,187 for “Method of Grinding Pharmaceutical Substances;” U.S. Pat.No. 5,718,388 for “Continuous Method of Grinding PharmaceuticalSubstances;” U.S. Pat. No. 5,862,999 for “Method of GrindingPharmaceutical Substances;” U.S. Pat. No. 5,665,331 for“Co-Microprecipitation of Nanoparticulate Pharmaceutical Agents withCrystal Growth Modifiers;” U.S. Pat. No. 5,662,883 for“Co-Microprecipitation of Nanoparticulate Pharmaceutical Agents withCrystal Growth Modifiers;” U.S. Pat. No. 5,560,932 for“Microprecipitation of Nanoparticulate Pharmaceutical Agents;” U.S. Pat.No. 5,543,133 for “Process of Preparing X-Ray Contrast CompositionsContaining Nanoparticles;” U.S. Pat. No. 5,534,270 for “Method ofPreparing Stable Drug Nanoparticles;” U.S. Pat. No. 5,510,118 for“Process of Preparing Therapeutic Compositions ContainingNanoparticles;” and U.S. Pat. No. 5,470,583 for “Method of PreparingNanoparticle Compositions Containing Charged Phospholipids to ReduceAggregation,” all of which are specifically incorporated by reference.

Milling to Obtain an Aripiprazole Prodrug Composition

Milling aripiprazole prodrug to obtain an aripiprazole prodrugcomposition according to the present invention comprises dispersing theparticles in a liquid dispersion medium in which the aripiprazoleprodrug is poorly soluble, followed by applying mechanical means in thepresence of grinding media to reduce the particle size of thearipiprazole prodrug to the desired volume based particle size (Dv50).The dispersion medium can be, for example, water, safflower oil,ethanol, t-butanol, glycerin, polyethylene glycol (PEG), hexane, orglycol. A preferred dispersion medium is water.

The aripiprazole prodrug particles can be reduced in size in thepresence of at least one surface stabilizer. Alternatively, aripiprazoleprodrug particles can be contacted with one or more surface stabilizersafter attrition. Other compounds, such as a diluent, can be added to thearipiprazole prodrug/surface stabilizer composition during the sizereduction process. Dispersions can be manufactured continuously or in abatch mode.

The grinding media can comprise particles that are preferablysubstantially spherical in shape, e.g., ceramic beads or beadsconsisting essentially of polymeric or copolymeric resin. Alternatively,the grinding media can comprise a core having a coating of a polymericor copolymeric resin adhered thereon.

In general, suitable polymeric or copolymeric resins are chemically andphysically inert, substantially free of metals, solvent, and monomers,and of sufficient hardness and friability to enable them to avoid beingchipped or crushed during grinding. Suitable polymeric or copolymericresins include crosslinked polystyrenes, such as polystyrene crosslinkedwith divinylbenzene; styrene copolymers; polycarbonates; polyacetals,such as Delrin™ (E.I. du Pont de Nemours and Co.); vinyl chloridepolymers and copolymers; polyurethanes; polyamides;poly(tetrafluoroethylenes), e.g., Teflon® (E.I. du Pont de Nemours andCo.), and other fluoropolymers; high density polyethylenes;polypropylenes; cellulose ethers and esters such as cellulose acetate;polyhydroxymethacrylate; polyhydroxyethyl acrylate; andsilicone-containing polymers such as polysiloxanes and the like. Thepolymer can be biodegradable. Exemplary biodegradable polymers orcopolymers include poly(lactides), poly(glycolide) copolymers oflactides and glycolide, polyanhydrides, poly(hydroxyethyl methacrylate),poly(imino carbonates), poly(N-acylhydroxyproline)esters,poly(N-palmitoyl hydroxyproline) esters, ethylene-vinyl acetatecopolymers, poly(orthoesters), poly(caprolactones), andpoly(phosphazenes). For biodegradable polymers or copolymers,contamination from the media itself advantageously can metabolize invivo into biologically acceptable products that can be eliminated fromthe body.

The grinding media preferably ranges in size from about 0.01 to about 3mm. For fine grinding, the grinding media is preferably from about 0.02to about 2 mm, and more preferably from about 0.03 to about 1 mm insize. The polymeric or copolymeric resin can have a density from about0.8 to about 3.0 g/cm³.

In a preferred grinding process the aripiprazole prodrug particles aremade continuously. Such a method comprises continuously introducing anaripiprazole prodrug composition according to the invention into amilling chamber, contacting the aripiprazole prodrug compositionaccording to the invention with grinding media while in the chamber toreduce the aripiprazole prodrug particle size of the compositionaccording to the invention, and continuously removing the aripiprazoleprodrug composition from the milling chamber. The grinding media isseparated from the milled aripiprazole prodrug composition according tothe invention using known separation techniques, in a secondary processsuch as by simple filtration, sieving through a mesh filter or screen,and the like. Other separation techniques such as centrifugation mayalso be employed.

An exemplary milling process using a Nanomill® 01 mill includes thefollowing steps:

-   -   1. Calculation of the quantity of active pharmaceutical        ingredient (API), surface stabilizer and other excipient needed        for the composition.    -   2. Preparation of the continuous phase or dispersion medium,        which includes the steps of weighing the excipients in a clean        vial and vortexing the contents for a number of seconds,        allowing the contents to sit for a short period of time        thereafter. For preparation of the 10X vehicle, for example,        sodium chloride may be dissolved in a citrate buffer. After        filtration, the vehicle may be then transferred into a sterile        container and stored in cold room.    -   3. Weighing the API and transferring the API into a milling        chamber.    -   4. Adding the dispersion medium to the API in the chamber.    -   5. Mixing the content to ensure the surfaces are wetted.    -   6. Weighing milling media and adding the media to the milling        chamber.    -   7. Mixing the contents of the chamber to ensure most of the        media is wetted.    -   8. Installing the chamber onto the NanoMill and connecting the        cooling bath.    -   9. Running the mill at its lowest setting for 5 minutes.    -   10. Milling the content at the desired tip speed and time.    -   11. Harvesting the milled composition. Where a Nanomill® 01 mill        is used, it has been noted that compositions with mean particle        size of less than 200 nm are best harvested by centrifuging        using a 10 μm harvesting tube or a 10 mL stainless steel        harvesting vessel with stainless steel screen having a mesh size        ranging from 100 to 150 μm. For compositions having mean        particle size of less than 250 nm, it is best to collect most of        the NCD using a 23 G needle first and then centrifuge the slurry        left using the 10 μm harvesting tube and to combine the two        portions thereafter.

An exemplary formulation using polysorbate 20 as a surface stabilizermay be prepared by milling crystals of aripiprazole lauroxil using aNanoMill at 30% (w/w) load in 2% (w/w) polysorbate 20. Dosingconcentration may be achieved thereafter by diluting the resultingdispersion with vehicle. The potency can be accurately determined byHPLC.

Wet-milling can be conducted in aqueous vehicles containing stabilizingsurface modifiers with polystyrene beads (Polymill® 500 milling media)using a NanoMill® 0.01 milling system. The milling shaft tip speed, themilling volume and the milling time may be adapted according to variousexperimental set-ups until the desired particle size is reached. “Stock”formulations can be harvested by pumping the dispersion through anappropriate filter (10 um polystyrene or 100 um metal mesh) atapproximately 30% (w/w) API load. The solid load, surface stabilizerconcentration, milling temperature, the milling shaft tip speed, themilling volume and the milling time may be adapted according to variousexperimental set-ups until the desired particle size is reached.

Precipitation to Obtain an Aripiprazole Prodrug Composition

Another method of forming an aripiprazole prodrug composition accordingto the present invention is by microprecipitation. This is a method ofpreparing stable dispersions of poorly soluble active agents in thepresence of one or more surface stabilizers and one or more colloidstability enhancing surface active agents free of any trace toxicsolvents or solubilized heavy metal impurities. Such a method comprises,for example: (1) dissolving aripiprazole prodrug in a suitable solvent;(2) adding the formulation from step (1) to a solution comprising atleast one surface stabilizer; and (3) precipitating the formulation fromstep (2) using an appropriate non-solvent. The method can be followed byremoval of any formed salt, if present, by dialysis or diafiltration andconcentration of the dispersion by known means.

Homogenization to Obtain an Aripiprazole Prodrug Composition

Exemplary homogenization methods of preparing active agent compositionsare described in U.S. Pat. No. 5,510,118, for “Process of PreparingTherapeutic Compositions Containing Nanoparticles.” Such a methodcomprises dispersing aripiprazole prodrug particles in a liquiddispersion medium, followed by subjecting the dispersion tohomogenization to reduce the particle size of aripiprazole prodrug tothe desired volume based particle size (Dv50). The aripiprazole prodrugparticles can be reduced in size in the presence of at least one surfacestabilizer. Alternatively, the aripiprazole prodrug particles can becontacted with one or more surface stabilizers either before or afterattrition. Other compounds, such as a diluent, can be added to thearipiprazole prodrug/surface stabilizer composition either before,during, or after the aripiprazole prodrug particle size reductionprocess. Dispersions can be manufactured continuously or in a batchmode.

Cryogenic Methodologies to Obtain an Aripiprazole Prodrug Composition

Another method of forming the aripiprazole prodrug composition of thepresent invention is by spray freezing into liquid (SFL). Thistechnology comprises an organic or organo-aqueous solution ofaripiprazole prodrug with surface stabilizers, which is injected into acryogenic liquid, such as liquid nitrogen. The droplets of aripiprazoleprodrug solution freeze at a rate sufficient to minimize crystallizationand particle growth, thus formulating aripiprazole prodrug particlesless than 1000 nm in size. Depending on the choice of solvent system andprocessing conditions, the aripiprazole prodrug particles can havevarying particle morphology. In the isolation step, the nitrogen andsolvent are removed under conditions that avoid agglomeration orripening of the aripiprazole prodrug particles.

As a complementary technology to SFL, ultra rapid freezing (URF) mayalso be used to created equivalent aripiprazole prodrug particles withgreatly enhanced surface area. URF comprises an organic ororgano-aqueous solution of aripiprazole prodrug with surface stabilizersonto a cryogenic substrate.

Emulsion Methodologies to Obtain an Aripiprazole Prodrug Composition

Another method of forming the aripiprazole prodrug composition of thepresent invention is by template emulsion. Template emulsion createsnanostructured aripiprazole prodrug particles with controlled particlesize distribution and rapid dissolution performance. The methodcomprises an oil-in-water emulsion that is prepared, then swelled with anon-aqueous solution comprising aripiprazole prodrug and surfacestabilizers. The particle size distribution of aripiprazole prodrug is adirect result of the size of the emulsion droplets prior to loading witharipiprazole prodrug, a property which can be controlled and optimizedin this process. Furthermore, through selected use of solvents andstabilizers, emulsion stability is achieved with no or suppressedOstwald ripening. Subsequently, the solvent and water are removed, andthe stabilized aripiprazole prodrug particles are recovered. Variousaripiprazole prodrug particle morphologies can be achieved byappropriate control of processing conditions.

Supercritical Fluid Methods of Making an Aripiprazole ProdrugComposition

Aripiprazole prodrug compositions can also be made using methodsemploying the use of supercritical fluids. In such a method aripiprazoleprodrug is dissolved in a solution or vehicle which can also contain atleast one surface stabilizer. The solution and a supercritical fluid arethen co-introduced into a particle formation vessel. If a surfacestabilizer was not previously added to the vehicle, it can be added tothe particle formation vessel. The temperature and pressure arecontrolled, such that dispersion and extraction of the vehicle occursubstantially simultaneously by the action of the supercritical fluid.Chemicals described as being useful as supercritical fluids includecarbon dioxide, nitrous oxide, sulphur hexafluoride, xenon, ethylene,chlorotrifluoromethane, ethane, and trifluoromethane.

Examples of known supercritical methods of making nanoparticles includeInternational Patent Application No. WO 97/14407 to Pace et al,published on Apr. 24, 1997, which refers to particles of water insolublebiologically active compounds with an average size of 100 nm to 300 nmprepared by dissolving the compound in a solution and then spraying thesolution into compressed gas, liquid, or supercritical fluid in thepresence of appropriate surface stabilizers.

Similarly, U.S. Pat. No. 6,406,718 to Cooper et al. describes a methodfor forming a particulate fluticasone propionate product comprising theco-introduction of a supercritical fluid and a vehicle containing atleast fluticasone propionate in solution or suspension into a particleformation vessel, the temperature and pressure in which are controlled,such that dispersion and extraction of the vehicle occur substantiallysimultaneously by the action of the supercritical fluid. Chemicalsdescribed as being useful as supercritical fluids include carbondioxide, nitrous oxide, sulphur hexafluoride, xenon, ethylene,chlorotrifluoromethane, ethane, and trifluoromethane. The supercriticalfluid may optionally contain one or more modifiers, such as methanol,ethanol, ethyl acetate, acetone, acetonitrile or any mixture thereof. Asupercritical fluid modifier (or co-solvent) is a chemical which, whenadded to a supercritical fluid, changes the intrinsic properties of thesupercritical fluid in or around the critical point. According to Cooperet al, the fluticasone propionate particles produced using supercriticalfluids have a particle size range of 1 to 10 μm, preferably 1 to 5 μm.

Nano-Electrospray Techniques Used to Obtain an Aripiprazole ProdrugComposition

In electrospray ionization a liquid is pushed through a very smallcharged, usually metal, capillary. This liquid contains the desiredsubstance, e.g., aripiprazole prodrug, dissolved in a large amount ofsolvent, which is usually much more volatile than the analyte. Volatileacids, bases or buffers are often added to this solution as well. Theanalyte exists as an ion in solution either in a protonated form or asan anion. As like charges repel, the liquid pushes itself out of thecapillary and forms a mist or an aerosol of small droplets about 10 μmacross. This jet of aerosol droplets is at least partially produced by aprocess involving the formation of a Taylor cone and a jet from the tipof this cone. A neutral carrier gas, such as nitrogen gas, is sometimesused to help nebulize the liquid and to help evaporate the neutralsolvent in the small droplets. As the small droplets evaporate,suspended in the air, the charged analyte molecules are forced closertogether. The drops become unstable as the similarly charged moleculescome closer together and the droplets once again break up. This isreferred to as Coulombic fission because it is the repulsive Coulombicforces between charged analyte molecules that drive it. This processrepeats itself until the analyte is free of solvent and is a lone ion.

In nanotechnology the electrospray method may be employed to depositsingle particles on surfaces, e.g., aripiprazole prodrug particles. Thisis accomplished by spraying colloids and ensuring that on average thereis not more than one particle per droplet. Consequent drying of thesurrounding solvent results in an aerosol stream of single aripiprazoleprodrug particles. Here the ionizing property of the process is notcrucial for the application but may be put to use in electrostaticprecipitation of the particles.

Particle Size Characterization

The particle size of the present composition may be measured usingtechniques such as light scattering with either water or a dilutesurface stabilizer solution as the diluent. Measurements may be verifiedusing microscopy. Particle size distributions may be determined using aHoriba 950 particle size analyser as a wet suspension. The volume basedparticle size (Dv50) is expressed herein by the mean volume diameter ofthe particles. Particle size measurement can also be carried out usingPCS (Dynamic light scattering measurements).

In addition to light scattering techniques, there are other methods fordetermining particle size as documented below.

Optical microscopy may be conducted on a Leica DMR microscope at 100×magnifications using Phase contrast optics. Image analysis may beperformed using Axiovision software.

Scanning electron microscopy (SEM) may be conducted using a suitablescanning electron microscope such as a Phenom Pro G2. Samples may beprepared by casting diluted formulation at about 0.5 mg/mL on to 9 mmPelcon carbon adhesive tabs, followed by air drying overnight. Thesamples may be sputter coated (2×) using a Denton Vacuum Desk V sputtercoater.

Free Surface Stabilizer

In order to ensure that the appropriate amount of free surfacestabilizer is present in the composition of the present invention, arough approximation of the amount of surface stabilizer that must beadded can be arrived at using the following theory. Note that thefollowing abbreviations are used SA=Surface Area, NP=Nanoparticle,PS=Particle Size. The presence of free surface stabilizer may beapproximately predicted according to the formulaSA_(stabilizer)/SA_(Available). If the resulting value is equal to 1then the system is saturated with surface stabilizer. If the resultingvalue is less than 1, this would indicate that the system will not besaturated, and therefore there will not be any free surface stabilizeravailable. If the value is determined to be greater than 1 then thesystem is saturated, and free stabilizer will be available.

In the above equation SA_(available) is the total surface area of drugsubstance available for a given mass. SA_(stabilizer) is the surfacearea of the stabilizer head groups adsorbed to the surface of the drugparticles. These values can be calculated by working out the totalsurface area based on the estimated radius of the drug particles. Theradius (r) is calculated simply by taking the value for the volume basedparticle size (Dv50) and dividing by 2, when using the assumption thatthe drug particles are spherical. The resultant value is then multipliedby the number of particles (N), which is determined by the mass of drugused (M) divided by the mass of one drug particle. The mass of oneparticle may be calculated from the density of the drug substance (6)multiplied by the volume of one particle (V_(np)), where V_(np)=4πr³/3.

N=M/σ*V _(np)

Surface area of one nanoparticle=SA_(NP)=4πr ²

Surface area total=SA_(total) =N*SA_(NP)

Due to packing of the surface stabilizer head groups not all surfacearea is available. This may be modelled by assuming the nanoparticle isa sphere and assuming that Hexagonal Close Pack (HCP) packing will givea maximum for packing on the surface. The HCP for two dimensionalcircles (which this model assumes the stabilizer head groups to be) is0.9069 (i.e. 90.69% of surface is covered).

SA_(available)=SA_(total)*0.9069

SA_(stabilizer)=Surface area of stabilizer head groups adsorbed to drugsurface.

The value for SA_(stabilizer) may be calculated as follows. First themass of stabilizer to be included in the composition is converted tomoles of stabilizer used. This is then used to calculate the number ofstabilizer molecules present, which is the number of moles*NA (where NAis Avagadro's constant=6.022*10⁻²³ mol⁻¹). The number of stabilizermolecules is then multiplied by the surface area of the head group. Thehead group area for Polysorbate 20 is taken to be the surface area ofthe aliphatic C12 chain. Values for the head group area may becalculated from the literature and will depend on the orientation ofthis group at the surface (Tween surfactants: Adsorption,self-organization, and protein resistance: Lei Shen, Athena Guo,Xiaoyang Zhu; Surface Science 605 (2011) 494-499).

The aforementioned technique provides an approximate guideline of thequantity of surface stabilizer to be added.

Measurement of Free Surface Stabilizer

The quantity of free surface stabilizer may be determined after thecompositions have been produced using techniques such asthermogravimetric analysis (TGA) or High-performance liquidchromatography (HPLC).

A method for determining a free component of surface stabilizer in anaripiprazole prodrug composition may comprise the following steps: (i)separating particles and the surface stabilizer adsorbed thereto fromthe dispersion medium to form a supernatant, and (ii) measuring thequantity of surface stabilizer in the supernatant using a highperformance liquid chromatography (HPLC) apparatus.

HPLC could be used to determine the quantity of free surface stabilizerusing for example reversed-phase HPLC analysis with a C8 column. Thisexemplified method is isocratic with 35% 10 mM Potassium phosphatebuffer (pH 2.5) and 65% acetonitrile as the mobile phase and UVdetection at 240 nm. The drug product is re-suspended andcentrifuged/filtered to remove the drug substance and “bound”polysorbate 20. The amount of “free” polysorbate 20 is quantitatedagainst polysorbate 20 standard solutions.

Method of Treatment and Use of the Aripiprazole Prodrug Composition ofthe Invention

The invention also provides a method of treating a mammal in needcomprising administering a stable aripiprazole prodrug compositioncomprising: (a) particles of aripiprazole prodrug or a salt thereofhaving a volume based particle size (Dv50) of less than about 1000 nm;and (b) at least one surface stabilizer.

The aripiprazole prodrug composition of the invention may be useful inthe treatment of diseases and disorders of the CNS, such as mentaldiseases and disorders, including but not limited to schizophrenia,acute manic and mixed episodes associated with bipolar disorder, andother schizophreniform illnesses, major depressive disorder (MDD), andtreatment of irritability associated with autistic disorder. The methodmay include treating a mammal, including a human, for disorders of thecentral nervous system, such as mental diseases or disorders; suchtreatments may include psychiatric treatment. The treatment may involveadministering to the mammal a composition comprising an aripiprazoleprodrug according to the present invention.

The composition of the invention can be administered to a subject viaany pharmaceutically acceptable means including, but not limited toparenterally (e.g., intramuscular, or subcutaneous).

A composition suitable for parenteral injection may comprisephysiologically acceptable sterile aqueous or nonaqueous solutions,dispersions, suspensions or emulsions, and sterile powders forreconstitution into sterile injectable solutions or dispersions.Examples of suitable aqueous and nonaqueous carriers, diluents,solvents, or vehicles including water, ethanol, polyols(propyleneglycol, polyethylene-glycol, glycerol, and the like), suitablemixtures thereof, vegetable oils (such as olive oil) and injectableorganic esters such as ethyl oleate. Proper fluidity can be maintained,for example, by the use of a coating such as lecithin, by themaintenance of the required particle size in the case of dispersions,and by the use of surfactants.

The composition may be administered in any pharmaceutically acceptableform; however, an injectable formulation is preferred.

For example, the injectable formulation may be administered as anintramuscular or subcutaneous injection so as to form a bolus or depot;the depot may allow for a prolonged duration of action, for example, bydissolving slowly and steadily into the subject's system. Thus, theinjectable formulations may be configured to allow for the controlledrelease of the aripiprazole prodrug after subcutaneous, intramuscular,intraperitoneal, etc. injection. For example, particle size andexcipient concentration may be adjusted to result in the controlledrelease (e.g., the blood levels of aripiprazole prodrug in the subject'sremain within an effective therapeutic window) greater than about 24hours, greater than about 3 days, for greater than about 5 days, forgreater than about 7 days, for greater than about 10 days, for greaterthan about 14 days, for greater than about 20 days, for greater thanabout 30 days, for greater than about 2 months, for greater than about 3months or for greater than about 4 months, or for any time period inbetween these values. The composition may be formulated such that theinjected depot may release aripiprazole prodrug at therapeutic levelsfor periods of from about two to about twenty-four weeks; from about twoto about six weeks; from about two to about four weeks; or from aboutone to about four weeks.

In the treatment of central nervous system disorders, it is useful toprovide a drug dosage form that delivers the required therapeutic amountof the drug in vivo and renders the drug bioavailable in a rapid andconsistent manner. These goals may be achieved using the injectableformulations of the aripiprazole prodrug composition described herein,via the formation of a depot (e.g., with intramuscular injection) asdescribed above. In some embodiments, the drug is released from thedepot into the blood stream at a constant rate, thus providing thepatient with the proper dose of the drug continuously for an extendedperiod of time. This method (e.g., depot injection) also results inimproved patient compliance. A single injection once per month, forexample, will provide the patient with the appropriate therapeuticdosage for the month, versus the daily struggle to remember or to decideto take a tablet, capsule, etc.

An exemplary injectable formulation of aripiprazole prodrug forintramuscular or subcutaneous administration may include aripiprazoleprodrug particles having a volume based particle size (Dv50) of lessthan 1000 nm and having one or more surface stabilizers, such as but notlimited to a polyoxyethylene sorbitan fatty acid ester (polysorbate 80,polysorbate 40, polysorbate 20), low molecular weight povidones,lecithin, d-alpha tocopheryl polyethylene glycol 1000 succinate, dioctylsodium sulfosuccinate, or docusate sodium), methyl and propyl parabens,sorbitan monolaurate, carboxymethyl cellulose, hydroxypropylcellulose,sodium deoxycholate, akylsaccharides, difunctional block copolymers,d-alpha tocopheryl polyethylene glycol 1000 succinate, gelatin, albumin,lysozyme, cyclodextrins (for example betahydroxcyclodextrin) and gelforming polymers, adsorbed on the surface thereof in an amountsufficient to maintain a volume based particle size (Dv50) for thedesired duration of efficacy. Such an aripiprazole prodrug compositionformulated for parenteral administration may enhance the efficacy ofaripiprazole prodrug in the treatment of various types of CNS diseasesor disorders, such as mental diseases and disorders.

A composition suitable for parenteral injection may comprisephysiologically acceptable sterile aqueous or nonaqueous solutions,dispersions, suspensions or emulsions, and sterile powders forreconstitution into sterile injectable solutions or dispersions.Examples of suitable aqueous and nonaqueous carriers, diluents,solvents, or vehicles including water, ethanol, polyols(propyleneglycol, polyethylene-glycol, glycerol, and the like), suitablemixtures thereof, vegetable oils (such as olive oil) and injectableorganic esters such as ethyl oleate. Proper fluidity can be maintained,for example, by the use of a coating such as lecithin, by themaintenance of the required particle size in the case of dispersions,and by the use of surfactants.

The aripiprazole prodrug composition may also comprise adjuvants such aspreserving, wetting, emulsifying, and dispensing agents. Prevention ofthe growth of microorganisms can be ensured by various antibacterial andantifungal agents, such as parabens, chlorobutanol, phenol, sorbic acid,and the like. It may also be desirable to include isotonic agents, suchas sugars, sodium chloride, and the like. Prolonged absorption of theinjectable pharmaceutical form can be brought about by the use of agentsdelaying absorption, such as aluminum monostearate and gelatin.

In addition, it is anticipated that a higher concentration of the formof aripiprazole prodrug may be delivered in a smaller injectable dosesize (and thus smaller volume) as compared to conventional forms ofaripiprazole prodrug. This ensures that any discomfort to the patientwhen administering is kept to a minimum.

The composition may also comprise adjuvants such as preserving, wetting,emulsifying, and dispensing agents. Prevention of the growth ofmicroorganisms can be ensured by various antibacterial and antifungalagents, such as parabens, chlorobutanol, phenol, sorbic acid, and thelike. It may also be desirable to include isotonic agents, such assugars, sodium chloride, and the like. Prolonged absorption of theinjectable pharmaceutical form can be brought about by the use of agentsdelaying absorption, such as aluminum monostearate and gelatin.

All publicly available documents referenced herein, including but notlimited to US patents, are specifically incorporated by reference.

EXAMPLES

The following examples are provided to illustrate the present invention.It should be understood, however, that the invention is not to belimited to the specific conditions or details described in theseexamples.

All units specified in terms of percentages (%) refer herein topercentage weight by weight (% w/w), i.e. the weight of the constituentis expressed as a percentage of the overall weight of the sampleprepared.

Horiba: refers to a Horiba LA 910 of LA 950 particle size analyser(Horiba Instruments, Irvine, Calif., USA).

For all of the below examples, milling was performed on a NanoMill® 0.01(Alkermes Pharma Ireland Limited) which has a chamber size of 10 ml, 50ml, or 100 ml along with a 500 μm or 250 μm Polymill® grinding media,which was supplied by Dow chemical Co., Michigan, United States(PolyMill® is a registered trademark of Alkermes Pharma IrelandLimited).

Unless otherwise indicated, materials were sourced as follows:Polysorbate 20, Sodium Citrate and Sodium chloride were supplied byAvantor™ Performance Materials supplied under its J.T.Baker® brand.Avantor Performance Materials, Inc, Philadelphia, USA. Phosphatebuffered saline was supplied by either EMD Millipore in the case ofsodium phosphate monobasic dihydrate (NaH₂PO₄ 2H₂O) or Avantor™Performance Materials, J.T.Baker® brand in the case of Sodium phosphatedibasic anhydrous (NaH₂PO₄). Arginine-HCL was supplied by Sigma-AldrichCo. LLC, St. Louis, Mo., USA. Aripirazole lauroxil and aripiprazolecavoxil may be produced as described in U.S. Pat. No. 8,431,576. Each ofthe formulations described below were produced from a solid particulateform, in the case of aripirazole cavoxil the particle size (Dv50) priorto milling was greater than 8 microns and in the case of aripiprazolelauroxil the particle size (Dv50) prior to milling was greater than 10microns.

In some cases, abbreviations are used for some components of thecomposition. For instance, PS20 signifies polysorbate 20, PBS signifiesphosphate buffered saline, CBS signifies citrate buffered saline. Allprinted publications referenced herein, including but not limited topatents, are specifically incorporated by reference.

Example 1 Rodent Study

The purpose of this study was to compare the pharmacokinetic propertiesof a dispersion of aripiprazole cavoxil having an volume based particlesize (Dv50) of less than 200 nm with a larger particle size dispersionof aripiprazole cavoxil.

Three samples were prepared as follows.

Formulation 1 was prepared according to the following steps. 4.66 g of acrude slurry of 13.6% (w/w) aripiprazole cavoxil and 1.6% (w/w)polysorbate 20 was first prepared. The mixture was then diluted byadding 10 mM buffer solution prepared from 0.8% (w/w) polysorbate 20 andthe remainder phosphate buffered saline. The slurry was then transferredto a NanoMill 0.01 having a 10 ml chamber and straight shaft. The slurrywas first mixed by hand with a spatula. The composition was milled for60 minutes at a milling speed of 2500 rpm (revolutions per minute). Themilling temperature during this process was 15° C. The resulting mixturewas collected using Vectaspin tubes, over a period of 10 minutes at atemperature of 10° C. and a milling speed of 2500 rpm. The finalcomposition as determined by potency assay comprised 8.39% (w/w)aripiprazole cavoxil, 1.6% (w/w) polysorbate 20, 10 mM phosphate bufferand 0.8% (w/w) sodium chloride. The drug to surface stabilizer ratio wasapproximately 5:1. Particle size analysis was performed on a HoribaLA950 using water as the observation medium (DDH20 at 79% T;RI=1.57-0.01i) and the composition was found to have a mean particlesize of 127 nm, with a Dv90 of 194 nm, a Dv50 of 120 nm and a Dv10 of 73nm.

Formulation 2 (comparator) was prepared as a comparator compositionhaving a particle size larger than the composition of the presentinvention. A crude slurry of 13.6% (w/w) aripiprazole cavoxil crystalsand 1.6% (w/w) Polysorbate 20 was first prepared and mixed for 1 hour.This was then diluted with a buffer solution comprising 1.6% (w/w)polysorbate 20 and phosphate buffered saline to the desired potency. Thefinal composition comprised approximately 8.8% (w/w) of aripiprazolecavoxil, 1.6% (w/w) polysorbate 20, 10 mM phosphate buffered saline, and0.8% (w/w) sodium chloride. The final composition was determined to havea pH of 6.9 with an osmolality of 279. Particle size analysis wasconducted on a Horiba LA910, observation medium was water with 0.1%(w/w) polysorbate 20. The composition was subjected to sonication over aperiod of 1 minute prior to the analysis. The composition was determinedto have a mean particle size of 28,000 nm (28 μm), with a Dv90 of 52,800 nm (52.8 μm) and a Dv10 of 3,774 nm (3.8 μm).

Formulation 3 (comparator) was an additional composition outside thescope of the present invention. This formulation comprised 8.3% (w/w)aripiprazole cavoxil, 2% (w/w) carboxy methyl cellulose, 0.2% (w/w)Polysorbate 20, 10 mM Phosphate buffer, and 0.6% (w/w) sodium chloride.The composition was sonicated for 1 minute prior to particle sizeanalysis on a Horiba LA 910 using a mixture of water and 0.1% (w/w)polysorbate 20 as the sizing medium. The composition was determined tohave a mean particle size of 26,200 nm (26.2 μm), a Dv10 of 3,616 nm(3.6 μm) and a Dv90 of 51,260 nm (51.3 μm).

All three formulations were stored at room temperature prior to dosing.Six rat subjects were used. The compositions were dosed intramuscularly,at a dose strength of approximately 20 mg, active concentration of 65mg/mL and a dose volume of 0.3 mL.

The pharmacokinetic properties measured as aripiprazole concentration inplasma are shown below in Table 1.

TABLE 1 Mean aripiprazole concentrations Mean aripiprazoleconcentrations (ng/ml) in rat plasma Formulation 2 Formulation 3Timepoint (hr) Formulation 1 (comparator) (comparator) 0.6 34.4 2.132.42 1 135 6.31 5.23 6 513 44.8 31.8 24 489 54.4 23.0 48 167 59.2 19.072 90.6 64.7 17.5 96 64.9 70.7 19.6 168 48.9 98.7 60.9 192 38.6 94.268.2 216 23.6 88.4 69.2 240 16.9 74.6 61.0

The mean aripiprazole concentration curves for Formulations 1, 2(comparator) and 3 (comparator) are shown in FIG. 2. The studydemonstrated that a formulation of aripiprazole cavoxil according to theinvention (Formulation 1) results in a significant change in the T_(max)observed in vivo. In this instance the T_(max) was shortened from 168hours in the case of a larger particle size comparator composition to 6hours in the case of a composition having a particle size of less than1000 nm as per the present invention, (i.e. a 28 fold decrease inT_(max), or a decrease of 96%).

Example 2 Rodent Study (Comparative Example)

A further rodent study was conducted as a comparative example in orderto determine the pharmacokinetic properties of a dispersion ofaripiprazole cavoxil having a particle size of just over 1000 nm.

Formulation 4 (comparator) was prepared as follows. A crude slurry of30% (w/w) aripiprazole cavoxil, 1.6% (w/w) polysorbate 20 and water wasprepared. This was then mixed for 5-10 minutes, before being transferredto a NanoMill 0.01, having 10 ml chamber and straight shaft. 500 μmPolyMill milling media was then added to make up a 69% (w/w) media load(4.21 g media). This was milled at 1500 rpm's for between 45 and 60minutes at 15° C. The concentration of this composition after harvestingwas 29% (w/w) aripiprazole cavoxil in 1.6% (w/w) polysorbate 20. Thiswas then diluted to the desired potency in a buffer solution comprising1.6% (w/w) polysorbate 20 and 10 mM phosphate buffered saline. The finalcomposition comprised 7.9% (w/w) aripiprazole cavoxil, 1.6% (w/w)polysorbate 20 in phosphate buffered saline, and had a pH of 7.03 and anosmolality of 253. Particle size analysis was performed on a Horiba 950using water as the diluent (RI=1.57-0.01i); where it was determined thatthe mean particle size was 1080 nm, the Dv90 was 1,740 nm, and the Dv50was 1,030 nm. The free component of surface stabilizer was determined tobe 21 ug/ml.

The study was performed using four rat subject subjects. Thecompositions were dosed intramuscularly, at a dose strength of 20 mg anda dose volume of 0.3 mL.

The mean aripiprazole concentration values as measured in whole bloodare shown in Table 2 below. These values are plotted in theconcentration curve depicted in FIG. 2, such that they are comparedagainst the respective concentration curves obtained for Formulations1-3 of Example 1.

TABLE 2 Mean aripiprazole concentrations Mean aripiprazoleconcentrations (ng/ml) in whole blood Timepoint (hr) Formulation 4(comparator) 0.5 2.14 2 18.3 6 65.2 24 34.4 48 32.4 72 33.4 96 41.9 16847.7 192 53.3 216 47.0 240 33.0

The data generated from this study demonstrates that a formulation ofaripiprazole cavoxil having a particle size of just over 1 μm exhibitspharmacokinetic properties which are very similar to those observed invivo in the case of Formulation 2 (comparator) and Formulation 3(comparator), both of which have particle sizes which are orders ofmagnitude greater the particle size of the present invention.

Example 3 Rodent Study

The purpose of the study was to compare the pharmacokineticcharacteristics of aripiprazole cavoxil compositions having a particlesize of between 200 nm and 1000 nm.

Formulations 5 and 6 were prepared in accordance with the formulationdetails set out below.

For Formulation 5, a crude slurry (total 5.86 g) was prepared comprising15% (w/w) aripiprazole cavoxil, 1.6% (w/w) polysorbate 20 and water. 500μm PolyMill milling media was added, the total amount being 4.21 g (i.e.69% media load). This was transferred to a NanoMill 0.01 having a 10 mlchamber and straight shaft and mixed by hand for 5 to 10 minutes using aspatula. The composition was milled at 2500 rpm for 55 minutes at 15° C.The milled composition was then collected using Vectaspin tubes. Theconcentration after harvesting was 13.7% (w/w) aripiprazole cavoxil,1.6% (w/w) polysorbate and the remainder water. This was then diluted tothe desired potency with a buffer solution of 1.6% (w/w) polysorbate 20and 10 mM phosphate buffered saline. The final composition comprised8.4% (w/w) aripiprazole cavoxil, 1.6% (w/w) polysorbate 20 and phosphatebuffered saline; and had a pH of 6.9 and an osmolality of 287 mOsm/kg.Particle size analysis was conducted on a Horiba 950 using water as thediluent (RI=1.57-0.01i); and the composition was determined to have amean particle size of 245 nm, with a Dv90 of 459 nm, a Dv50 of 200 nm,and a Dv10 of 91 nm.

For Formulation 6, a crude slurry (total 5.86 g) comprising 15% (w/w)aripiprazole cavoxil and 1.6% (w/w) polysorbate 20 in water wasprepared. 500 μm PolyMill milling media was added (i.e. 69% (w/w) mediaload or 4.21 g. The slurry was added to a NanoMill 0.01 having a 10 mlchamber and straight shaft, and mixed for 5 to 10 minutes using aspatula. The composition was then milled at 1500 rpm for 45 minutes andcollected using a syringe. The concentration of the respectivecomponents after harvesting was determined to be 12.9% (w/w)aripiprazole cavoxil, 1.6% (w/w) polysorbate 20 and water. This wasdiluted to the desired potency with a buffer solution, again 1.6% (w/w)polysorbate 20 and 10 mM phosphate buffered saline. The finalcomposition was 8.1% (w/w) aripiprazole cavoxil and 1.65% (w/w)polysorbate 20 in phosphate buffered saline. The measured pH was 7.0with an osmolality of 281 mOsm/kg. Particle size analysis on a Horiba950 with water as the sizing medium (RI-1.57-0.01i) determined that themean particle size of the composition was 475 nm, with a Dv90 of 942 nm,a Dv50 of 363 nm and a Dv10 of 143 nm.

The study was performed using 4 rat subjects. The compositions weredosed intramuscularly, at a dose strength of 20 mg and a dose volume of0.3 mL. The mean aripiprazole concentrations as measured in vivo inplasma at various time points are set out in Table 3 and plotted in thearipiprazole concentration curves shown in FIG. 3.

TABLE 3 Mean aripiprazole concentrations Mean aripiprazoleconcentrations (ng/ml) in plasma Timepoint (hr) Formulation 5Formulation 6 0.5 35.5 25.8 1 88.2 53 6 280 182 10 254 161 24 167 131 48106 103 72 71.3 72.6 168 104 126 240 41.6 47.8

The results of this study suggest that a smaller particle size showed ahigher exposure of aripiprazole.

Example 4 Rodent Study

This study focussed on aripiprazole lauroxil in an in-vivo model. Theobjective of this study was to examine whether changes inpharmacokinetic properties (e.g. reduction in onset time or T_(max))could be achieved by reducing the particle size to the sub-1000 μm rangewere achievable in the case of aripiprazole lauroxil. The study comparedthe pharmacokinetic properties of formulations of aripiprazole lauroxilhaving a particle size range according to the present invention withformulations of aripiprazole lauroxil whose size range lies outside thescope of the present invention.

Formulation 7 comprised aripiprazole lauroxil and was prepared asfollows. 5.86 g of a crude slurry of 30% (w/w) aripiprazole lauroxil, 2%(w/w) polysorbate 20 and water was first prepared. This was mixed for5-10 minutes prior to being milled in a NanoMill 0.01 having a 10 mlbucket and straight shaft. The milling media used was 500 μm PolyMill(4.21 g added, 69% (w/w) media load). The composition was milled at 2500rpm for a period of 35 minutes at 15° C. After harvesting, the milledcomposition was diluted to the desired potency with water and 10 mMcitrate buffered saline. The final composition comprised 9.2% (w/w)aripiprazole lauroxil, 0.67% (w/w) polysorbate 20 in 10 mM Citratebuffered saline.

The pH was determined to be 6.6 and the osmolality was 281 mOsm/kg.Particle size analysis was carried out on a Horiba 950 using water asthe diluent (RI: 1.62-0.01i) and the mean particle size was determinedto be 174 nm, with a Dv90 of 286 nm, a Dv50 of 157 nm and a Dv10 of 82nm.

Formulations 8 and 9 were prepared from the same milled slurry, anddiffered only in the sense that Formulation 9 was prepared without anybuffer, tonicity agents or hypotonic agents. The crude slurry for bothFormulation 8 and 9 comprised 30% (w/w) aripiprazole lauroxil, 2% (w/w)polysorbate 20 and water. The crude slurry was calculated at 5.86 g intotal. This was mixed for 5-10 minutes prior to being milled in aNanoMill 0.01 having a 10 ml bucket and straight shaft. The millingmedia used was 500 μm PolyMill (4.21 g added, 69% (w/w) media load). Thecomposition was milled at 2500 rpm for a period of 30 minutes at 15° C.After harvesting, In the case of Formulation 8, the milled compositionwas diluted to the desired potency with 10 mM citrate buffered saline.The final composition comprised 9.56% (w/w) aripiprazole lauroxil, and0.67% (w/w) polysorbate 20 in 10 mM Citrate buffered saline. The pH wasdetermined to be 6.3 and the osmolality was 229 mOsm/kg. Particle sizeanalysis was conducted on a Horiba 950 using water as the diluent (RI:1.62-0.01i) and the mean particle size was determined to be 687 nm witha Dv50 of 649 nm, a Dv90 of 1134 nm and a Dv10 of 284 nm. In the case ofFormulation 9, the dilution used just water. The final compositioncomprised 9.41% (w/w) aripiprazole lauroxil, 0.67% (w/w) polysorbate 20in water and had a pH of 6.4. The particle size distribution was verysimilar to Formulation 8 above (the mean was 584 nm, the Dv50 was 549nm, the Dv90 was 961 and the Dv10 was 261)

Formulation 10 was an un-milled comparator comprising 10% (w/w)aripiprazole lauroxil+2% (w/w) polysorbate 20 (LSC12-226) in CitrateBuffered Saline. The composition was prepared and stirred overnightbefore dosing. Final pH was 6.2 with an osmolality of 264 mOsm/kg. Themean particle size was measured at 17,000 nm, with a Dv90 of 28,300 nm,a Dv50 of 14,200 nm, and a Dv10 of 7,500 nm.

The formulations were dosed in rats and dosing details are provided inTable 4 below. The column labelled ARI dose depicts the aripirazoleequivalent dose value in miligrams.

TABLE 4 (Summary of dosing details for rodent study) Dose ARI Formu- APIPS20 Mean Level Dose Osmolality lation level (%) Ratio Milling (nm)(mg/ml) (mg) pH (mOsm/kg) Vehicle 7 30 2 15:1 135 min @ 200 63 100 6.6281 10 mM citrate, 2500 rpm 0.8% salt 8 30 2 15:1 30 min @ 540 65 1006.3 229 10 mM citrate, 2500 rpm 0.8% salt 9 30 2 15:1 30 min @ 540 64100 6.4 12 Water for 2500 rpm injection 10 10 2  5:1 Stirred at 22000 63100 6.2 264 10 mM citrate, 300 rpm 0.8% salt overnight

The mean aripiprazole values as measured in vivo over the various timepoints are depicted in Table 5 below. These values are also plotted inFIG. 4.

TABLE 5 Mean aripiprazole concentrations Mean aripiprazoleconcentrations (ng/ml) in whole blood Timepoint (hr) Formulation 7Formulation 8 Formulation 9 0.5 35.5 25.8 16.4 1 88.2 53 42.8 6 280 182114 10 254 161 100 24 167 131 75.6 48 106 103 61.3 72 71.3 72.6 45.6 96168 104 126 51.4 192 216 240 41.6 47.8 18.3

The results indicate that reducing the particle size of aripiprazolelauroxil to less than 1000 nm provides a faster onset and reducedT_(max) in comparison to a larger particle size comparator formulationhaving a Dv50 of 14,200 nm (Formulation 10). Such properties are usefulin the context of a lead-in formulation. This study provided a basis forfurther studies with aripiprazole lauroxil examining the effect ofparticle size in the sub-1000 nm range.

Example 5 Dog Study

The purpose of this study was to examine the respective pharmacokineticprofiles obtained for aripiprazole lauroxil composition having aparticle size of about 350 nm, about 450 nm and a mixed population ofparticles when dosed in vivo in dogs.

Formulation 11: A crude slurry (total 73 g) was prepared which comprised30% (w/w) aripiprazole lauroxil, 2% (w/w) polysorbate 20 and water. Themixture was milled on a NanoMill® 0.01 mill having a 50 ml bucket andpegged shaft, at 300 rpm for 5 minutes and at 1300 rpm for 330 minutes.500 μm PolyMill milling media was used, and the total media load was 69%(w/w). The resulting mixture was hand collected in a laminar flow hoodusing a 5 ml syringe and a 23 gauge needle, potency tested and thendiluted. The final composition was comprised of 14.3% (w/w) aripiprazolelauroxil and 1% (w/w) polysorbate 20 in 10 mM citrate buffered salineand had a pH of 6.3 and an osmolality of 320 mOsm/kg. Particle sizeanalysis conducted on a Horiba 950 (sizing medium was water) and it wasdetermined that the mean particle size was 395 nm; the Dv90 was 623 nm;the Dv50 was 368 nm; and the Dv10 was 205 nm.

Formulation 12: A crude slurry (total 73 g) was prepared which comprisedaripiprazole lauroxil 30% (w/w), 2% (w/w) polysorbate 20 as the surfacestabilizer and water. 1.6% (w/w) arginine HCl was added as a buffer. Thecomposition was milled on a NanoMill® 0.01 mill having a 50 ml bucketand pegged shaft, and using 500 μm PolyMill media at a media loading of69% (w/w). The milling temperature was maintained at 15° C. Thecomposition was milled at 300 rpm for 5 minutes and subsequently milledat 1300 rpm for 335 minutes. The milled composition was then handcollected in a laminar flow hood using a 5 ml syringe and a 23 gaugeneedle, potency tested and then diluted. The composition was thendiluted to the desired potency with Arginine-HCL solution. The finalcomposition comprised 14.9% (w/w) aripiprazole lauroxil, 1% (w/w)polysorbate 20 and 1.6% (w/w) Arginine hydrochloride. Particle sizeanalysis was conducted on a Horiba 950 using water as the sizing medium,where it was determined that the mean particle size was 465 nm; the Dv90was 794 nm, the Dv50 was 447 nm, and the Dv10 was 231 nm. The pH asmeasured was 5.7, with an osmolality of 182 mOsm/Kg.

Formulation 13: This composition was prepared in order to determine theproperties of a composition according to the present invention, wherebya lead in is combined with a larger particle size component. A mixedparticle size population was prepared by combining particles fromFormulation 11 with particles of 19,000 nm in size. The micrometer sizedparticles were prepared by mixing 30% (w/w) aripiprazole lauroxil in 2%(w/w) Polysorbate and leaving the mixture overnight.

The particles of Formulation 11 and the micrometer sized particles weremixed on a 1:1 weight basis, and were diluted to the desiredconcentration using Citrate Buffered Saline. The final compositioncomprised 73.5 mg/ml of Formulation 11, 73.5 mg/ml of the micrometersized particles, 10 mM CBS, and water. In total, the dosed compositioncomprised 10.3% (w/w) aripiprazole lauroxil, 1% (w/w) polysorbate 20 inCitrate Buffered Saline and had a pH of 6.6 and an osmolality of 324mOsm/kg.

A portion of Formulations 11, 12 and 13 was retained for stabilitytesting. The data generated from the stability test is outlined below inTable 6. The data indicates that the compositions are stable over thethree month period of testing.

TABLE 6 Stability of Formulations 12-15 over 3 month period StabilityStorage Formulation time point Temperature Mean (nm) Mean (nm) No.(months) (° C.) pH mOs/kg 1.44-001i 1.62-000i Formulation 0 (initial)6.6 ND 403 378 11 3 5 7.15 321 407 394 3 25 7.22 319 428 416 3 40 7.04321 495 529 Formulation 0 (initial) 5.7 ND 509 532 12 3 5 5.43 183 433422 3 25 5.21 181 594 787 3 40 4.98 182 750 1135 Formulation 0 (initial)240 13 -Peak A 3 5 220 3 25 220 3 40 263 Formulation 0 (initial) 1900013 - Peak B 3 5 13500 3 25 11000 3 40 21700

The number of dogs dosed in the dog study was 4 per formulation. Thedogs were dosed intramuscularly. Samples for pharmacokinetic analysiswere collected at regular intervals from dosing until 672 hours (28days) post dosing.

The concentration of aripiprazole in each respective sample wasmeasured. The mean pharmacokinetic parameters (for all of the dogs inthe study) as measured in whole blood is presented in Table 7 below.

TABLE 7 Pharmacokinetic parameter (Aripiprazole) T_(max) C_(max)AUC_(last) T_(1/2) Dose (hr) (ng/mL) (ng * hr/mL) (hr) Aripiprazole 3368.1 ± 1.8 2910 ± 778 174 ± 43  lauroxil (approx. 20 μm) formulationFormulation 11 204 9.0 ± 4.7 1893 ± 277 89 ± 32 Formulation 12 240 10.0± 4.0  2625 ± 981 96 ± 14 Formulation 13 204 4.2 ± 0.8 1359 ± 394 284 ±159

The results indicate that Formulations 11, 12 and 13 exhibits a reducedtime to T_(max) in comparison to a larger formulation having a particlesize of approximately 20 microns. For Formulation 11 a relatively highearly exposure to prodrug moiety was observed. For Formulation 13 a fastonset of aripiprazole concentration was observed followed by extendedcoverage of aripiprazole concentration over time was observed. FIG. 5depicts the mean aripiprazole concentrations as measured in vivo.

Example 6 Dog Study

Building on the findings of the previous study described which suggesteda faster onset and reduced T_(max) in the pharmacokinetic properties ofa composition according to the present invention in comparison tocompositions having a larger aripiprazole prodrug particle size, the aimof this study was to examine more specifically the impact of usingvarious aripiprazole prodrug particle sizes within the sub 1000 nm rangedefining the composition of the present invention. Furthermore, thestudy aimed to determine the pharmacokinetic profile achievable by usinga mixture of a formulation of the size range specified by the presentinvention (less than 1000 nm), with a larger particle size formulationof aripiprazole lauroxil.

Formulation 14: A crude slurry (total 53 g) comprising 13% (w/w)aripiprazole lauroxil composition and 1.3% (w/w) polysorbate 20 whichwas used as the surface stabilizer was prepared. The ratio ofaripirazole lauroxil to surface stabilizer was therefore about 10:1. 10mM Citrate buffered saline was added as a buffer. The composition wasmilled in a Nanomill 0.01 having a chamber volume of 100 ml using astraight (pegless) shaft, at a milling speed of 973 rpm for 240 minutesat a temperature of 15° C. The media used was 500 μm Polymill millingmedia, and the media load was 69%. The final particle size analysis on aHoriba LA 950 determined a mean particle size of 110 nm, a Dv90 of 164nm a Dv50 of 103 nm and a Dv10 of 67 nm.

Formulation 15: A crude slurry (5.86 g) comprising 15% (w/w)aripiprazole lauroxil and 1% (w/w) polysorbate 20 which was used as thesurface stabilizer was first prepared. The total ratio of aripirazolelauroxil to stabilizer was therefore 15:1. Citrate buffered saline wasadded as a buffer. The composition was milled in a Nanomill 0.01 havinga chamber volume of 10 ml using a straight shaft, at a milling speed of2500 rpm for 105 minutes at a temperature of 15° C. The media used was500 μm Polymill milling media, and the media load was 69%. The meanparticle size of the final composition as measured on a Horiba LA 950was 192 nm, with a Dv90 of 347, a Dv50 of 153 nm and a Dv10 of 77 nm.

Formulation 16 was a mixture of 100 mg of a composition having a volumebased particle size (Dv50) of approximately 100 nm (Formulation 16above) with 100 mg of a larger particle size composition of aripirazolelauroxil having a volume based particle size (Dv50) of approximately 20μm (20,000 nm). Citrate buffered saline was added as a buffer.

Formulation 17: A crude slurry (53 g) comprising 13% (w/w) aripiprazolelauroxil was perpared. Polysorbate, 1.3% (w/w) and 2% (w/w) dextrosewere added as surface stabilizers. The total ratio of aripiprazolelauroxil to stabilizer was about 10:1. Arginine was added as a buffer.Milling of the composition was carried out using a NanoMill 0.01 havinga chamber volume of 100 ml and a straight shaft. The milling speed was973 rpm and the composition was milled for 240 minutes at 15° C. Themilling media was 500 μm PolyMill milling media. The media load of 69%.The mean particle size as measured on a Horiba LA 950 was 105 nm, with aDv90 of 155 nm, a Dv50 of 97 nm and a Dv10 of 65 nm.

A total of 4 dogs per formulation were used in the study and all doseswere intramuscularly administered. Formulation 14 was dosed at a levelequivalent to 100 mg of aripirazole or 147 mg of aripiprazole lauroxiland the dose volume was 1.1 ml per animal. Formulation 15 was dosed at alevel equivalent to 100 mg of aripirazole or 147 mg of aripiprazolelauroxil and the dose volume was 1 ml per animal. Formulation 16 wasdosed at a level equivalent to 200 mg of aripiprazole (100 mg attributedto each particle size component in the mixture) or 147 mg ofaripiprazole lauroxil and the dose volume was 2.1 ml per animal.Formulation 17 was dosed at a level equivalent to 100 mg of aripirazoleor 147 mg of aripiprazole lauroxil and the dose volume was 1.1 ml peranimal. Samples for pharmacokinetic analysis were collected at regularintervals from dosing until 672 hours (28 days) post dosing.

The collected samples of whole blood were analyzed. The concentrationsof aripiprazole lauroxil and aripiprazole were measured. The meanconcentration values for aripiprazole are shown in Table 8 below.

TABLE 8 Mean aripiprazole concentrations for Formulations 14-17 Meanaripiprazole concentration in whole blood Formulation 16 TimeFormulation 14 Formulation 15 (100 + Formulation 17 (hrs) (100 nm) (150nm) 20,000) (100 nm) 2 12.00 2.20 7.31 5.12 6 15.10 5.38 8.77 4.62 1211.18 7.63 7.05 6.30 24 18.07 12.54 10.26 12.64 36 12.56 8.26 6.69 7.3048 16.38 9.46 11.76 12.83 72 13.55 8.17 9.11 12.05 120 8.06 6.53 5.457.28 168 7.02 8.28 4.08 5.62 240 7.50 6.39 3.48 2.46 336 5.11 2.45 2.361.27 408 4.08 2.07 1.66 2.68 504 3.56 1.65 1.15 576 2.2 1.01 672 1.98

TABLE 9 Pharmacokinetic parameters for analyte aripiprazole T_(max)C_(max) AUC_(last) T_(1/2) Dose (hr) (ng/mL) (ng * hr/mL) (hr)Aripiprazole 336  8.1 ± 1.8 2910 ± 778 174 ± 43 lauroxil (20 μm)formulation Formulation 14 24 12.8 ± 5.6 1661 ± 147 110 ± 54 Formulation15 24 12.8 ± 5.2 2613 ± 684 118 ± 47 Formulation 16 48 19.0 ± 9.7  4152± 1128 228 ± 86 Formulation 17 36 14.9 ± 6.2 1854 ± 431 104 ± 66

TABLE 10 Pharmacokinetic parameters for analyte aripiprazole lauroxil(prodrug) C_(max) AUC_(last) T_(1/2) Dose (ng/mL) (ng * hr/mL) (hr)Aripiprazole 4.53 112.7 332 lauroxil (20 μm) formulation Formulation 14441 4201 16.7 Formulation 15 47.4 597 13.7 Formulation 16 500 4824 26Formulation 17 215 2812 25

FIG. 6 depicts the mean aripiprazole concentrations as measured in vivoin a dog model for Formulations 14 to 17. All of formulations 14 to 17were noted to have a reduced onset time and T_(max) when compared to thearipiprazole lauroxil formulation of approximately 20 microns in size.

Example 7 Dog Study

The purpose of this example was to determine the Pharmacokineticparameters for various aripiprazole compositions in an animal model. Thestudy focused in particular on the effect of dose level and quantity ofsurface stabilizer on levels of aripiprazole prodrug and aripiprazolemeasured in vivo in dogs.

Formulation 18: A crude slurry (116 g) was first prepared in whichPolysorbate 20 was used as a surface stabilizer at a level of 2% (w/w).A citrate buffer was used at an amount of 15:1. Milling of thecomposition was carried out using a NanoMill 0.01 having a chambervolume of 100 ml and a pegged shaft. The milling was initially conductedat a speed of 3100 rpm for 45 minutes and then at 700 rpm for 20minutes. The milling temperature was 15° C. 500 μm PolyMill millingmedia was used. The media load was 89%. Total dose strength wasequivalent to 100 mg of aripiprazole. The particle size distribution asmeasured after formulation was found to have a Dv90 value of 296.8 nm, aDv50 value of 166.1 nm, and a Dv10 value of 84.0 nm.

Formulation 19: A crude slurry (58 g) was first prepared in whichPolysorbate 20 was used as a surface stabilizer at a level of 1% (w/w).A citrate buffer was used at an amount of 28:1. Milling took placed on aNanoMill 0.01 mill having a 50 ml chamber and a pegged shaft. Themilling speed was 962 rpm for 180 minutes which was reduced to 450 rpmfor 60 minutes thereafter. The milling process took place at atemperature of between 8 and 10° C. The media used was 500 μm PolyMillmilling media. The total media load was 89%. Total dose strength wasequivalent to 300 mg of aripiprazole. The particle size distribution asmeasured after formulation was found to have a Dv90 value of 679.1 nm, aDv50 value of 242.6 nm, and a Dv10 value of 88.1 nm.

Formulation 20: A crude slurry (116 g) was first prepared in whichPolysorbate 20 was used as a surface stabilizer at a level of 2% (w/w).A citrate buffer was used at an amount of 15:1. Milling was carried outusing a NanoMill 0.01 mill having a chamber volume of 100 ml and apegged shaft. The milling speed was 3100 rpm for 45 minutes and 700 rpmfor 20 minutes. The milling temperature was 15° C. The media used was500 μm PolyMill milling media. The media load was 89%. Total dosestrength was equivalent to 300 mg of aripiprazole. The particle sizedistribution as measured after formulation was found to have a Dv90value of 296.8 nm, a Dv50 value of 166.1 nm, and a Dv10 value of 84.0nm.

Formulation 21: A crude slurry (116 g) was first prepared in whichPolysorbate 20 was used as a surface stabilizer at a level of 3% (w/w).A citrate buffer was used at an amount of 10:1. Milling was carried outusing a NanoMill 0.01 having a 100 ml chamber and pegged shaft. Themilling speed was initially 3100 rpm for a period of 4 minutes, reducedto 389 rpm for 50 minutes, then increased to 3100 rpm for 40 minutes andfinally reduced to 450 rpm for 90 minutes. The milling temperature was8° C. The media used was 500 μm PolyMill milling media. The total mediaload was 89%. The final dose strength of the composition was equivalentto 300 mg of aripiprazole. The particle size distribution as measuredafter formulation was found to have a Dv90 value of 361.8 nm, a Dv50value of 151.8 nm, and a Dv10 value of 76.4 nm.

Formulation 22: A crude slurry (total 116 g) was first prepared in whichPolysorbate 20 was used as a surface stabilizer at a level of 2% (w/w).A phosphate and sodium citrate buffer was used at an amount of 15:1.Milling was carried out using a NanoMill 0.01 having a 100 ml chamberand pegged shaft. The milling speed was initially 3100 rpm for a periodof 45 minutes which was then reduced to 700 rpm for 20 minutes. Themilling temperature was 15° C. The media used was 500 μm PolyMillmilling media. The total media load was 89%. Total dose strength wasequivalent to 300 mg of aripiprazole. The particle size distribution asmeasured after formulation was found to have a Dv90 value of 306 nm, aDv50 value of 171 nm, and a Dv10 value of 86 nm.

Formulation 23: A crude slurry (total 116 g) was first preparedcomprising Polysorbate 20 used as a surface stabilizer at a level of 2%(w/w). A citrate buffer was used at an amount of 15:1. Milling wascarried out using a NanoMill 0.01 having a 100 ml chamber and peggedshaft. The milling speed was initially 3100 rpm for a period of 45minutes which was then reduced to 700 rpm for 20 minutes. The millingtemperature was 15° C. The media used was 500 μm PolyMill milling media.The total media load was 89%. Total dose strength was equivalent to 700mg of aripiprazole. The particle size distribution as measured afterformulation was found to have a Dv90 value of 296.8 nm, a Dv50 value of166.1 nm, and a Dv10 value of 84.0 nm.

Formulation 24: A crude slurry (total 116 g) was first preparedcomprising Polysorbate 20 was used as a surface stabilizer at a level of2% (w/w). A citrate/sucrose buffer was used at an amount of 15:1.Milling was carried out using a NanoMill 0.01 having a 100 ml chamberand pegged shaft. The milling speed was initially 3100 rpm for a periodof 45 minutes which was then reduced to 700 rpm for 20 minutes. Themilling temperature was 15° C. The media used was 500 μm PolyMillmilling media. The total media load was 89%. Total dose strength wasequivalent to 300 mg of aripiprazole. The particle size distribution asmeasured after formulation was found to have a Dv90 value of 301 nm, aDv50 value of 168 nm, and a Dv10 value of 84 nm.

A total of 4 dogs were used for each formulation. All formulations weredosed intramuscularly. Formulation 18 was dosed at a level of 147 mgaripiprazole lauroxil (equivalent to 100 mg aripiprazole) and the dosevolume was 0.67 ml per animal. Formulations 19, 20, 21, 22 and 24 weredosed at a level of 441 mg aripiprazole lauroxil (equivalent to 300 mgof aripiprazole) and the dose volume was 2 ml per animal. Formulation 23was dosed at a level of 1029 mg of aripiprazole lauroxil (equivalent to700 mg of aripirazole) and the dose volume was 4.7 ml per animal.

The mean aripiprazole concentrations as measured in whole blood areshown below in Table 11. These values are also plotted in FIGS. 7 and 8.FIG. 7 directly compares the mean aripiprazole concentrations asmeasured in vivo for Formulations 18, 20 and 23. FIG. 8 directlycompares the mean aripiprazole concentrations as measured in vivo forFormulations 19, 20 and 21.

TABLE 11 Mean aripiprazole concentrations Mean aripiprazoleconcentration in whole blood (ng/ml) Time Formu- Formu- Formu- Formu-Formu- Formu- Formu- point lation 18 lation 19 lation 20 lation 21lation 22 lation 23 lation 24 (hr) (~160 nm) (~250 nm) (~160 nm) (~150nm) (~170 nm) (~160 nm) (~170 nm) 0.5 — — — 2.24 — — — 2 — — 1.78 8.944.73 3.36 2.12 6 1.58 1.27 3.53 12.73 7.85 11.07 5.058 12 1.91 2.35 3.166.37 4.19 13.66 5.20 24 1.63 2.81 6.45 19.90 13.43 17.43 9.27 36 2.303.93 9.48 30.35 17.85 28.33 10.55 48 1.92 3.99 10.13 32.85 14.50 28.7511.54 72 2.67 2.90 10.01 33.80 17.98 30.28 10.00 120 3.60 6.14 18.0235.20 16.68 28.91 14.14 168 2.71 8.26 17.97 36.48 18.18 27.00 18.75 2403.82 13.58 24.75 18.93 16.58 26.23 20.38 336 2.29 9.00 10.42 11.36 6.5026.70 14.53 408 1.73 9.48 5.56 7.45 8.47 11.31 6.19 504 1.96 7.70 4.273.13 4.09 13.51 5.46 576 1.06 4.23 3.49 4.33 6.17 9.24 3.21 672 — 3.111.96 2.25 4.01 6.33 2.44

The mean pharmacokinetic parameters for aripiprazole levels ascalculated for each group are shown in Table 12 shown below.

TABLE 12 Pharmacokinetic parameters for analyte aripiprazole C_(max)AUC_(last) Dose (ng/mL) (ng * hr/mL) Formulation 18 14 1539 Formulation19 13.9 5518 Formulation 20 26.6 7258 Formulation 21 45.9 10449Formulation 22 23 8402 Formulation 23 39.1 15248 Formulation 24 21.27595

From the results obtained the following conclusions can be reachedregarding the effect of dose level on exposure. Formulation 18 containeda 100 mg dose of aripirazole, Formulation 23 contained a 700 mg dose andFormulations 19-22 and 24 contained a 300 mg dose. It is noted thatincreasing the dose did lead to an increase in the level of aripiprazolelauroxil (prodrug) detected in the blood. Secondly, it is noted that thelevel of aripiprazole measured was increased by increasing the dose.

With regard to the effect of the percentage of polysorbate 20 present onthe overall prodrug exposure, the following observations were made.Formulation 19 had the lowest level of polysorbate 20 at 1% (w/w) of theoverall composition. Formulations 18, 20, 22, 23 and 24 had a higherlevel at 2% (w/w) and Formulation 21 had the highest level at 3% (w/w).It was found that increasing the percentage of polysorbate 20 in thecomposition resulted in a higher free component of the dose.Accordingly, the level of aripiprazole and prodrug in blood was found tobe increased by increasing the percentage of polysorbate 20 present.

Example 8 Dog Study

The purpose of this final dog study was to determine the effect ofparticle size and active surface stabilizer ratio on the levels ofaripiprazole lauroxil and aripiprazole measured in whole blood followinga single intramuscular injection in dogs. The samples were preparedessentially of the same constituents, whereby either the particle sizeof the aripiprazole lauroxil particles was varied and/or the totalquantity of surface stabilizer present was varied. The formulations wereprepared as follows:

Formulation 25 was prepared from a crude slurry (total 136 g) comprising26% w/w aripirazole lauroxil and 1.53% w/w polysorbate 20 as a surfacestabilizer (i.e. approximately 17:1 ratio of active to surfacestabilizer). To this, 10 mM phosphate buffered saline (pH 6.8) was addedalong with 26 mM of sodium citrate. (Polymill milling media of 250 μm insize was added in an amount to bring the total media load to 80%. Theslurry was placed inside a 100 ml chamber of a NanoMill® 0.01 millhaving a pegged shaft and milled at 1000 rpm for a total of 1860 minutesat a temperature of 5° C. The final composition prior to dosing had amean particle size of 113 nm, a Dv90 of 166 nm, a Dv50 of 107 nm and aDv10 of 69 nm.

Formulation 26 was prepared from a crude slurry (total 136 g) comprising26% w/w aripiprazole lauroxil and 1.53% w/w polysorbate 20 as a surfacestabilizer (i.e. approximately 17:1 ratio of active to surfacestabilizer). To this, 10 mM phosphate buffered saline (pH 6.8) was addedalong with 26 mM of sodium citrate. Polymill milling media of 500 μm insize was added, such that the total media load was 80%. The slurry wasmilled in a NanoMill® 0.01 mill having a 100 ml chamber and pegged shaftat 1000 rpm for 723 minutes at a milling temperature of 5° C. The finalcomposition had a mean particle size of 202 nm, a Dv90 of 366 nm, a Dv50of 167 nm, and a Dv10 of 82 nm.

The viscosity of Formulation 26 was determined at various shear rates ata temperature of 25° C. At a shear rate of 1 s⁻¹, the viscosity wasdetermined to be about 9 cP. The viscosity profile was observed tofollow a shear thinning type profile where a Newtonian region wasobserved between 100 and 1000 s⁻¹, with the shear rate being maintainedat approximately 3.5-4 cP. This test shows that Formulation 26 hasfavourable viscosity characteristics in the context of an injectableformulation where the shear rate is generally increased when injectingthe composition. FIG. 18 depicts the viscosity versus shear curve forFormulation 26.

Formulation 27 was prepared from a crude slurry (total 136 g) comprising26% w/w aripirazole lauroxil and 1.53% w/w polysorbate 20 as a surfacestabilizer (i.e. approximately 17:1 ratio of active to surfacestabilizer). To this, 10 mM phosphate buffered saline (pH 6.8) was addedalong with 26 mM of sodium citrate. Polymill milling media having a sizeof 500 μm was added, the total media load being 80%. The slurry wasplaced inside a 100 ml chamber of a NanoMill® 0.01 mill having a peggedshaft and milled at 1000 rpm for a total of 538 minutes at a temperatureof 5° C. The final composition had a mean particle size of 445 nm, aDv90 of 769 nm, a Dv50 of 398 nm, and a Dv10 of 180 nm.

Formulation 28 was prepared from a crude slurry (total 136 g) comprising26% w/w aripirazole lauroxil and 1.73% w/w polysorbate 20 as a surfacestabilizer (i.e. approximately 15:1 ratio of active to surfacestabilizer). To this, 10 mM phosphate buffered saline (pH 6.8) was addedalong with 26 mM of sodium citrate. Polymill milling media of 250 μm insize was added in an amount to bring the total media load to 80%. Theslurry was milled in a NanoMill® 0.01 mill having a 100 ml chamber andpegged shaft, at 1000 rpm for a total of 1200 minutes at a millingtemperature of 5° C. The final composition was found to have a meanparticle size of 109 nm, a Dv90 of 161 nm, a Dv50 of 102 nm, and a Dv10of 68 nm.

Formulation 29 was prepared from a crude slurry (total 136 g) comprising26% w/w aripirazole lauroxil and 2.6% w/w polysorbate 20 as a surfacestabilizer (i.e. approximately 10:1 ratio of active to surfacestabilizer). To this, 10 mM phosphate buffered saline (pH 6.8) was addedalong with 26 mM of sodium citrate. Polymill milling media of 250 μm insize was added in an amount to bring the total media load to 80%. Theslurry was placed inside a 100 ml chamber of a NanoMill® 0.01 millhaving a pegged shaft and milled at 1000 rpm for a total of 1200 minutesat a temperature of 5° C. The final composition was found to have a meanparticle size of 113 nm, a Dv90 of 168 nm, a Dv50 of 106 nm and a Dv10of 68 nm.

Formulation 30 was prepared from a crude slurry (total 136 g) comprising26% w/w aripirazole lauroxil and 1% w/w polysorbate 20 as a surfacestabilizer (i.e. approximately 26:1 ratio of active to surfacestabilizer). To this, 10 mM phosphate buffered saline (pH 6.8) was addedalong with 26 mM of sodium citrate. Polymill milling media of 500 μm insize was added in an amount to bring the total media load to 80%. Theslurry was placed inside a 100 ml chamber of a NanoMill® 0.01 millhaving a pegged shaft and milled at 1000 rpm for a total of 90 minutesat a temperature of 5° C. The final composition was found to have a meanparticle size of 449 nm, a Dv90 of 765 nm, a Dv50 of 407 nm, and a Dv10of 184 nm.

For each of the Formulations 25-30 described above, the level of freesurface stabilizer and the dissolved aripiprazole lauroxil wasdetermined experimentally using HLPC analysis as set out in Table 13below. For some of the formulations the amount of free surfacestabilizer or the dissolved aripiprazole lauroxil was less than thelevel of detection, abbreviated <LOD in the Table.

TABLE 13 Measurement of free surface stabilizer in compositionApproximate % w/w of particle size and total % w/w of DissolvedFormulation API:surface surface free surface API number stabilizer ratiostabilizer stabilizer (μg/mL) Formulation 25 100 nm 17:1 1.5 <LOD <LODFormulation 26 200 nm 17:1 1.5 0.24 1.51 Formulation 27 450 nm 17:1 1.50.65 3.73 Formulation 28 100 nm 15:1 1.7 <LOD <LOD Formulation 29 100 nm10:1 2.6 0.75 3.83 Formulation 30 450 nm 26:1 1.0 <LOD <LOD

Each of the aforementioned Formulations 25-30 were dosed intramuscularlyinto 4 male dogs. For each formulation, the dose level per animal wasequivalent to 300 mg of aripiprazole or 441 mg of aripiprazole lauroxil.For each dosed sample, the target dose volume was 1.6 mL per animal.Whole blood was collected over the following time points post dosing(hours): 0.25, 0.5, 1, 2, 3, 6, 12, 24, 36, 48, 60, 72, 120, 168, 240,336, 408, 504, 576, and 672. The levels of aripiprazole and aripiprazolelauroxil were analyzed in whole blood over the aforementioned timepoints, the mean values are respectively depicted in Table 14 and Table15 below.

TABLE 14 Mean aripiprazole concentration values Aripiprazoleconcentration in whole blood (ng/ml) Formu- Formu- Formu- Formu- Formu-Formu- lation 25 lation 26 lation 27 lation 28 lation 29 lation 30 100nm 200 nm 450 nm 100 nm 100 nm 450 nm Time 17:1 17:1 17:1 15:1 10:1 26:10.25 0.50 3.33 1.49 1.77 1 1.46 1.94 1.115 3.27 5.05 2 2.14 2.77 1.35.61 9.86 1.63 3 1.85 3.29 1.97 6.11 12.80 2.50 6 1.70 5.59 2.35 5.5712.93 2.48 12 3.06 7.30 4.48 6.34 12.13 5.14 24 4.53 10.02 7.15 8.3014.37 9.34 36 5.18 12 7.19 8.80 22.11 9.71 48 4.77 9.75 9.60 8.94 22.4911.47 60 6.80 10.54 8.74 10.09 28.13 11.63 72 6.58 8.33 13.55 11.0835.36 15.48 120 24.33 19.55 39.70 37.25 45.58 37.53 168 9.43 8.22 11.9411.34 11.57 17.68 240 9.81 9.60 10.2 8.53 11.15 18.64

TABLE 15 Mean aripiprazole lauroxil concentrations Mean aripiprazolelauroxil concentration (ng/ml) Formu- Formu- Formu- Formu- Formu- Formu-lation 25 lation 26 lation 27 lation 28 lation 29 lation 30 Time 100 nm200 nm 450 nm 100 nm 100 nm 450 nm (hr) 17:1 17:1 17:1 15:1 10:1 26:10.25 7.28 140.16 166.03 219.85 222.95 13.52 0.5 5.07 50.40 138.80 168.01176.55 13.26 1 15.91 156.47 72.85 197.35 52.20 17.30 2 10.66 150.5071.03 129.28 112 20.82 3 8.1 116 49.58 124.15 212.70 14.37 6 9.93 76.2824.94 70.05 191.53 9.14 12 6.57 33.25 17.41 45.68 76.99 9.62 24 4.8110.71 10.91 14.21 24.15 8.31 36 3.03 8.59 7.02 9.81 18.84 7.03 48 3.194.40 6.20 10.28 14.27 5.74 60 5.36 6.92 7.18 12.78 14.25 7.01 72 3.873.69 6.66 10.37 10.31 6.09 120 17.35 5.26 5.57 13.33 9.01 6.07 168 3.331.46 1.99 3.17 2.60 2.92 240 2.09 1.40 3.54 1.62

The data indicates that for a given particle size distribution (forexample 100 nm) when the amount of the surface stabilizer is increasedin the formulation, the exposure of aripiprazole lauroxil increases.FIGS. 11 and 16 illustrates the area under the curve (AUC) foraripiprazole lauroxil determined following intramuscular administrationin dogs of formulations 25, 28 and 29. Similarly, the exposure ofaripiprazole increases as a function of surface stabilizer (FIGS. 17 and12). This is explained by the fact that at a fixed particle size, i.e.surface area, surface stabilizer will adhere to the surface of theparticles until all surfaces are covered, any excess stabilizer presentin the formulation vehicle is referred to as free stabilizer. As theamount of free stabilizer increases the solubility of the aripiprazolelauroxil increases. This is supported by the in-vitro data depicted inTable 13 and illustrated in FIG. 18. As more aripiprazole lauroxil isdissolved the exposure in the dog model increases and consequentlyaripiprazole exposure increases.

Similar behaviour is also observed for formulations 27 and 30 withlarger particle size; i.e. smaller surface area (FIGS. 13, 19A and 20).

Despite the fact that Formulations 25 and 30 have different particlesize with 100 nm and 450 nm, respectively, the two formulations have nodetectable amount of free polysorbate 20 or dissolved aripiprazolelauroxil (FIG. 21). The reason is that the drug to stabilizer ratio isdifferent. Formulation 26 has same drug to stabilizer ratio but withlarger particle size (smaller surface area) as formulation 25. As aresult, formulation 26 has higher amount of free polysorbate 20 anddissolved aripiprazole lauroxil (FIG. 21).

FIG. 22 compares the AUC of aripiprazole lauroxil and aripiprazole forformulations 25, 26 and 30. Although formulation 26 has smaller particlesize than formulation 25, aripiprazole lauroxil and aripiprazoleexposure are higher for formulation 26. This is due to the manipulationin the drug to stabilizer ratio which lead to the difference in theamount of free polysorbate 20 and consequently the amount of dissolvedaripiprazole lauroxil in the formulation. Such manipulation did overcomethe effect of particle size (surface area) on dissolution where smallerparticle sizes dissolve faster.

Similar correlation can be drawn when comparing formulations 25 and 30.Even though, formulations 25 and 30 have very different particle size,the release profiles of the two formulations in dog are similar (FIGS.14, 15 and 19B).

FIG. 9 and FIG. 10 depict the mean aripiprazole lauroxil concentrationsas measured in vivo for Formulations 25-27 where the drug to API ratiois fixed and the particle size is varied. Formulation 26 showing that anintermediate particle (200 nm) size in comparison to Formulation 25 (100nm) and 27 (450 nm) has a higher initial exposure of aripiprazole andaripiprazole lauroxil.

Example 9

In order to demonstrate that the compositions of the present are sizestable, a number of studies were conducted, some of which are describedbelow.

Formulation 31 was prepared in order to assess the stability of acomposition according to the present invention. A four week stabilitystudy was conducted on a formulation comprising 20% aripiprazolelauroxil. The composition had a 14:1 aripiprazole lauroxil to surfacestabilizer ratio. In addition, 10 mM Phosphate buffered saline and 26 mMcitrate buffered saline were added as buffers. FIG. 17 is a plot ofparticle size measurements over various timepoints demonstrating theformulation stability for Formulation 31. As evidenced by the data inthe plot, the composition was found to exhibit very little particle sizegrowth over the study period.

In addition to producing compositions stability studies were alsocarried out in relation to a number of other formulations as summarisedbelow in Table 16 below.

TABLE 16 6 month stability analysis of alternative formulations Tem- T =0 1 mth 3 mth 6 mth Formulation perature Mean Mean Mean Mean Summary (°C.) (nm) (nm) (nm) (nm) Aripirazole 2-8 200 200 210 260 Lauroxil 200 nmstabilized with PS 20 30% (w/w) API + 2% (w/w) PS20 Aripirazole 2-8 200No data 220 250 Lauroxil 200 nm stabilized with PS 20 Citrate-Sucrose 25No data No data 230 280 27% API + 40 No data No data 250 390 1.8% PS20 +Citrate Buffered Sucrose Aripirazole 2-8 200 No data 220 250 Lauroxil200 nm stabilized with PS 20 25 No data 230 240 300 27% API + 1.8% 40 Nodata 310 No data 570 PS20 + Citrate Buffered Saline Aripirazole 2-8 480540 570 590 Lauroxil 500 nm stabilized with PS 20 30% API + 2% PS20Aripirazole 2-8 530 No Data 530 530 Lauroxil 500 nm stabilized with PS20 27% API + 25 No Data 550 650 360 with 1.8% PS20 + Sediment CitrateBuffered Sucrose 40 No Data 780 Aggregate NA Aripirazole 2-8 480 No Data610 660 Lauroxil 500 nm stabilized with PS 20 25 No Data 580 720 780 27%API + 40 No Data 780 760 800 1.8% PS20 + Citrate Buffered Saline

Example 10

Although polysorbate 20 is a preferred choice of surface stabilizer, thepresent invention may also be realised using alternative surfacestabilizers. To demonstrate this, Formulation 32 was prepared, whichcomprised aripiprazole cavoxil particles which were stabilized with betahydroxyl cyclodextrin. The composition as prepared comprised 5% w/waripiprazole cavoxil and 10% beta hydroxyl cyclodextrin. The finalcomposition had a particle size of approximately 250 nm and wasdemonstrated to have very little particle size growth over a four weekperiod as outlined in Table 17 below.

TABLE 17 4 week stability analysis for Formulation 32 StorageTemperature Time Dv10 (° C.) (weeks) Mean (nm) (nm) Dv50 (nm) Dv90 (nm)4 0 269 199 255 362 1 243 172 233 325 4 255 181 245 334 25 1 266 190 259348 4 293 195 268 388

Example 11

At the time of writing, Formulations 33-36 discussed below are due to bedosed as part of a human study. Formulations 33, 34 and 35 are largelyvery similar to Formulations 25, 26 and 30 prepared for the dog studydiscussed in Example 8 above.

Formulation 33 will be prepared from a crude slurry comprising 26% w/waripiprazole lauroxil and 1.53% w/w polysorbate 20 as a surfacestabilizer (i.e. approximately 17:1 ratio of active to surfacestabilizer). To this, 10 mM phosphate buffer (pH 6.8) will be addedalong with 26 mM of citrate buffered saline. The formulation will bemilled in a similar manner to Formulation 30 discussed above in order toproduce a final volume based particle size before dosing of about 100 nm(+−50 nm).

Formulation 34 will be prepared from a crude slurry comprising 26% w/waripirazole lauroxil and 1.53% w/w polysorbate 20 as a surfacestabilizer (i.e. approximately 17:1 ratio of active to surfacestabilizer). To this, 10 mM phosphate buffer (pH 6.8) will be addedalong with 26 mM of citrate buffered saline. The formulation will bemilled in a similar manner to Formulation 31 discussed above in order toproduce a final volume based particle size before dosing of about 200 nm(+−50 nm).

Formulation 35 will be prepared from a crude slurry comprising 26% w/waripirazole lauroxil and 1% w/w polysorbate 20 as a surface stabilizer(i.e. approximately 26:1 ratio of active to surface stabilizer). Tothis, 10 mM phosphate buffer (pH 6.8) will be added along with 26 mM ofcitrate buffered saline. The formulation will be milled in a similarmanner to Formulation 35 discussed above in order to produce a finalvolume based particle size before dosing of about 450 nm (+−50 nm).

Formulation 36 will be prepared from a crude slurry comprising 26% w/waripiprazole lauroxil, 1% w/w polysorbate 20 (forming a drug:surfacestabilizer ratio of 26:1) in 10 mM phosphate buffer, pH 6.8. 26 mMcitrate buffered saline is added as a buffer. The aforementionedcomposition will be milled such that the final particle size will beapproximately 900 nm (+−50 nm). The composition details for Formulation33-36 are summarised in Table 18 below.

TABLE 18 Details of compositions for human study Formulation FormulationFormulation Formulation 33 34 35 36 Component (w/w %) (w/w %) (w/w %)(w/w %) Aripiprazole 26 26 26 26 Lauroxil Polysorbate 20 1.53 1.53 1 1Sodium Citrate 0.76 0.76 0.76 0.76 Sodium 0.31 0.31 0.31 0.31 chlorideSodium 0.15 0.15 0.15 0.15 phosphate Buffer Water for 71.25 71.25 71.7871.78 Injection

It is anticipated that each of the aforementioned compositions willexhibit a faster onset and reduced T_(max) in pharmacokinetic propertieswhen dosed in humans, and in particular that the onset time will begreatly improved in comparison to larger particle size formulations, inparticular the 20 μm aripiprazole formulation described in the previousexamples of the present specification.

Example 12

Effect of secondary stabilizer on PK in rodent model:

Formulation X was prepared from a crude slurry (total 5.86 g) comprising15% w/w aripirazole cavoxil and 1.6% w/w polysorbate 20 as a surfacestabilizer (i.e. approximately 9:1 ratio of active to surfacestabilizer). Polymill milling media having a size of 500 μm was added,the total media load being 69%. The slurry was placed inside a 10 mlchamber of a NanoMill® 0.01 mill having a straight shaft and milled at1500 rpm for a total of 45 minutes at a temperature of 15° C. A portionof this batch was diluted to 8% aripirazole cavoxil with 1.6%polysorbate 20 in phosphate buffer saline (pH 6.8). The finalcomposition had a mean particle size of 584 nm, the Dv50 was 549 nm, theDv90 was 961 and the Dv10 was 261. Formulation Y was prepared bydiluting the other portion of the above batch was diluted to 8%aripirazole cavoxil with 1.6% polysorbate 20 in phosphate buffer saline(pH 6.8) and 0.1% pluronic F108 as a secondary stabilizer. The finalcomposition had a mean particle size of 584 nm, the Dv50 was 549 nm, theDv90 was 961 and the Dv10 was 261.

Formulations X and Y were stored at room temperature prior to dosing.Six rat subjects were used. The compositions were dosed intramuscularly,at a dose strength of approximately 20 mg, active concentration of 65mg/mL and a dose volume of 0.3 mL.

The mean aripiprazole concentration curves for Formulations X and Y areshown in FIG. 25. The study demonstrated that by adding a secondarystabilizer a significant change in the C_(max) was observed in vivo. Thearipiprazole exposure increase significantly (5 times) in formulation Ycompared to X.

Observation under the microscope for a drop of formulation X diluted inphosphate buffer saline showed aggregates formation (FIG. 26). On theother hand, when formulation Y was diluted in phosphate buffer saline,the formulation showed no aggregation under the microscope. This mightindicate that when injected into the intramuscular space, formulation Xmight form aggregates which reduce the surface area in contact with themuscle. On the other hand, formulation Y might form an injection depotthat is spread between the muscles which increases the surface areacontact thus leads to increase in exposure.

While certain of the preferred embodiments of the present invention havebeen described and specifically exemplified above, it is not intendedthat the invention be limited to such embodiments. Various modificationsmay be made thereto without departing from the scope and spirit of thepresent invention.

1. A composition comprising: (a) a population of particles of anaripiprazole prodrug having a volume based particle size (Dv50) of lessthan about 1000 nm as determined by light scattering techniques, (b) atleast one surface stabilizer comprising an adsorbed component which isadsorbed on the surface of the aripiprazole prodrug particles and a freecomponent available for solubilisation of the aripiprazole prodrug,wherein the ratio of aripiprazole prodrug to surface stabilizer isbetween about 0.1:1 and about 40:1, and wherein the aripiprazole prodrughas the formula:

where n is zero or an integer less than
 20. 2. The composition of claim1, wherein in the aripiprazole prodrug formula n is equal to
 4. 3. Thecomposition of claim 1, wherein in the aripiprazole prodrug formula n isequal to
 10. 4. The composition of claim 1, wherein the free componentof the at least one surface stabilizer constitutes greater than 0% (w/w)and no more than about 3% (w/w) of the composition.
 5. The compositionof claim 1, wherein the volume based particle distribution size (Dv50)of the aripiprazole prodrug particles is between about 50 and about 700nm.
 6. The composition of claim 5, wherein the volume based particledistribution size (Dv50) is between about 175 nm and about 350 nm. 7.The composition of claim 1, wherein the at least one surface stabilizeris selected from the group consisting of a polyoxyethylene sorbitanfatty acid ester (polysorbate 80, polysorbate 40, polysorbate 20), lowmolecular weight povidones, lecithin, d-alpha tocopheryl polyethyleneglycol 1000 succinate, dioctyl sodium sulfosuccinate, or docusatesodium), methyl and propyl parabens, sorbitan monolaurate, carboxymethylcellulose, hydroxypropylcellulose, sodium deoxycholate, akylsaccharides,difunctional block copolymers, d-alpha tocopheryl polyethylene glycol1000 succinate, gelatin, albumin, lysozyme, cyclodextrins and gelforming polymers.
 8. The composition claim 1, wherein the at least onesurface stabilizer is selected from the group consisting ofcarboxymethyl cellulose and polyoxyethylene sorbitan fatty acid esters.9. The composition of claim 8, wherein the at least one surfacestabilizer is a polyoxyethylene sorbitan fatty acid ester.
 10. Thecomposition claim 1, wherein the at least one surface stabilizer ispolysorbate
 20. 11. The composition of claim 1, comprising a primarysurface stabilizer and at least one secondary surface stabilizer. 12.The composition of claim 1, wherein the ratio of aripiprazole prodrug tosurface stabilizer present in the composition is within the range fromabout 17:1 to about 26:1.
 13. The composition of claim 1, furthercomprising a dispersion medium in which the population of aripiprazoleprodrug particles is dispersed, wherein the free component of thesurface stabilizer is dissolved or otherwise dispersed within thedispersion medium.
 14. The composition of claim 1, adapted foradministration as a depot injection.
 15. The composition of claim 1,wherein the composition is provided in an injection device.
 16. Thecomposition of claim 15, wherein: (a) the injection device is apre-filled syringe; (b) the injection device is an auto-injector; (c)the injection device is a needleless syringe; or (d) the injectiondevice is a dual chambered syringe.
 17. The composition of claim 16,wherein the injection device is a dual chambered syringe and thearipiprazole prodrug composition is provided in one chamber of the dualchambered syringe, and the other chamber of the dual chamber syringe isprovided with a second composition.
 18. The composition of claim 17,wherein the second composition is an aripiprazole prodrug composition,having a volume based particle size (Dv50) of at least 200 nm, of atleast 300 nm, of at least 400 nm, of at least 500 nm, of at least 600nm, of at least 700 nm, of at least 800 nm, of at least 900 nm, of atleast 1000 nm, of at least 1500 nm, of at least 2000 nm, of at least5000 nm, of at least 10,000 nm greater than the aripiprazole prodrugcomposition.
 19. The composition of claim 17, wherein the secondcomposition is an atypical antipsychotic other than an aripiprazoleprodrug.
 20. The composition of claim 1, formulated as a powder forreconstitution in a liquid medium, wherein the population ofaripiprazole prodrug particles redisperse in the liquid medium such thatthe redispersed aripiprazole prodrug particles have a volume basedparticle size (Dv50) of less than 1000 nm.
 21. The composition of claim1, further comprising a second population of aripiprazole prodrugparticles, said second population having a volume based particle size(Dv50) of about 5000 nm or greater.
 22. The composition of claim 21,wherein the second population has a volume based particle size (Dv50) ofabout 15 μm to about 25 μm.
 23. The composition of claim 1, furthercomprising an additional atypical antipsychotic other than thearipiprazole prodrug.
 24. The composition of claim 1, wherein theviscosity of the composition is below about 10 cP at a shear rate ofabout 100 s⁻¹, when measured at a temperature of about 25° C.
 25. Thecomposition of claim 1, whereby the composition when dosed in amammalian subject exhibits a T_(max) of less than one week in the bloodof the subject and wherein the concentration of aripiprazole in theblood is maintained above a therapeutically effective amount for aperiod of at least two weeks from the point in time where theconcentration of aripiprazole in the blood first reaches saidtherapeutically effective amount.
 26. The composition of claim 1,whereby the composition when dosed in a mammalian subject reaches atherapeutic concentration in the blood of the subject: (a) in less thanabout 36 hours and maintains a therapeutic level in the blood of thesubject for a minimum of about 5 days and a maximum of about 9 days; (b)in less than about 72 hours and maintains a therapeutic level in theblood of the subject for a minimum of about 5 days and a maximum ofabout 13 days; or (c) in less than about 7 days, and maintains aconcentration of aripiprazole in the blood of the subject which is abovethe therapeutic concentration for a minimum of about 14 days.
 27. Acomposition consisting of a population of particles of the formula:

having a volume based particle distribution size (Dv50) between about350 nm and about 175 nm as determined by light scattering techniques,wherein the ratio of said particles to polysorbate 20 is 17:1.
 28. Acomposition consisting of a population of particles of the formula:

having a volume based particle distribution size (Dv50) less than about400 nm as determined by light scattering techniques, wherein the ratioof said particles to polysorbate 20 is 17:1.
 29. A compositionconsisting of a population of particles of the formula:

having a volume based particle distribution size (Dv50) less than about300 nm as determined by light scattering techniques, wherein the ratioof said particles to polysorbate 20 is 17:1.
 30. A compositionconsisting of a population of particles of the formula:

having a volume based particle distribution size (Dv50) less than about200 nm as determined by light scattering techniques, wherein the ratioof said particles to polysorbate 20 is 17:1.
 31. A compositionconsisting of a population of particles of the formula:

having a volume based particle distribution size (Dv50) less than about100 nm as determined by light scattering techniques, wherein the ratioof said particles to polysorbate 20 is 17:1.
 32. A method of treating amammal having a condition selected from the group consisting ofschizophrenia, bipolar I disorder, major depressive disorder (MDD),autistic disorder, agitation associated with schizophrenia, and bipolarI disorder, wherein said method comprises administering a composition ofaripiprazole prodrug composition comprising: a population of particlesof an aripiprazole prodrug having a volume based particle size (Dv50) ofless than about 1000 nm as determined by light scattering techniques,and at least one surface stabilizer comprising an adsorbed componentwhich is adsorbed on the surface of the aripiprazole prodrug particlesand a free component available for solubilisation of the aripiprazoleprodrug, wherein the ratio of aripiprazole prodrug to surface stabilizeris between about 0.1:1 and about 40:1, and wherein the aripiprazoleprodrug has the formula:

where n is zero or an integer less than
 20. 33. The method of claim 32,wherein said treatment further comprises administering a secondcomposition of aripiprazole prodrug having a volume based particle size(Dv50) of greater than about 5000 nm to the mammal.
 34. A method ofimproving initial in vivo pharmacokinetic release profile consisting ofproviding a population of particles of the formula:

having a volume based particle distribution size (Dv50) is between about350 and about 175 nm as determined by light scattering techniques,wherein a 17:1 ratio of said particles to polysorbate 20 achieves atherapeutic concentration of aripiprazole in less than about seven days.35. The method of claim 34, wherein said therapeutic concentration ofaripiprazole is achieved in less than about 72 hours.
 36. The method ofclaim 34, wherein said therapeutic concentration of aripiprazole isachieved in less than about 48 hours.
 37. The method of claim 34,wherein said therapeutic concentration of aripiprazole is achieved inless than about 24 hours.
 38. The method of claim 34, wherein saidvolume based particle distribution size (Dv50) is less than about 400nm, less than about 300 nm, less than about 200 nm, or less than about100 nm.
 39. The method of claim 34, wherein the therapeuticconcentration of aripiprazole is achieved with the concurrentadministration of a 30 mg dose of oral aripiprazole.